Merge branch 'main' into model-test-refactor

* fix torchao quantizer for new torchao versions

Summary:

`torchao==0.16.0` (not yet released) has some bc-breaking changes, this
PR fixes the diffusers repo with those changes. Specifics on the
changes:
1. `UInt4Tensor` is removed: https://github.com/pytorch/ao/pull/3536
2. old float8 tensors v1 are removed: https://github.com/pytorch/ao/pull/3510

In this PR:
1. move the logger variable up (not sure why it was in the middle of the
   file before) to get better error messages
2. gate the old torchao objects by torchao version

Test Plan:

import diffusers objects with new versions of torchao works:

```bash
> python -c "import torchao; print(torchao.__version__); from diffusers import StableDiffusionPipeline"
0.16.0.dev20251229+cu129
```

Reviewers:

Subscribers:

Tasks:

Tags:

* Apply style fixes

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

docs/source/en/api/pipelines/wan.md

@@ -250,6 +250,9 @@ The code snippets available in [this](https://github.com/huggingface/diffusers/p
 
 The general rule of thumb to keep in mind when preparing inputs for the VACE pipeline is that the input images, or frames of a video that you want to use for conditioning, should have a corresponding mask that is black in color. The black mask signifies that the model will not generate new content for that area, and only use those parts for conditioning the generation process. For parts/frames that should be generated by the model, the mask should be white in color.
 
+</hfoption>
+</hfoptions>
+
 ### Wan-Animate: Unified Character Animation and Replacement with Holistic Replication
 
 [Wan-Animate](https://huggingface.co/papers/2509.14055) by the Wan Team.

src/diffusers/quantizers/torchao/torchao_quantizer.py

@@ -36,6 +36,9 @@ from ...utils import (
 from ..base import DiffusersQuantizer
 
 
+logger = logging.get_logger(__name__)
+
+
 if TYPE_CHECKING:
     from ...models.modeling_utils import ModelMixin
 
@@ -83,11 +86,19 @@ def _update_torch_safe_globals():
     ]
     try:
         from torchao.dtypes import NF4Tensor
-        from torchao.dtypes.floatx.float8_layout import Float8AQTTensorImpl
-        from torchao.dtypes.uintx.uint4_layout import UInt4Tensor
         from torchao.dtypes.uintx.uintx_layout import UintxAQTTensorImpl, UintxTensor
 
-        safe_globals.extend([UintxTensor, UInt4Tensor, UintxAQTTensorImpl, Float8AQTTensorImpl, NF4Tensor])
+        safe_globals.extend([UintxTensor, UintxAQTTensorImpl, NF4Tensor])
+
+        # note: is_torchao_version(">=", "0.16.0") does not work correctly
+        # with torchao nightly, so using a ">" check which does work correctly
+        if is_torchao_version(">", "0.15.0"):
+            pass
+        else:
+            from torchao.dtypes.floatx.float8_layout import Float8AQTTensorImpl
+            from torchao.dtypes.uintx.uint4_layout import UInt4Tensor
+
+            safe_globals.extend([UInt4Tensor, Float8AQTTensorImpl])
 
     except (ImportError, ModuleNotFoundError) as e:
         logger.warning(
@@ -123,9 +134,6 @@ def fuzzy_match_size(config_name: str) -> Optional[str]:
     return None
 
 
-logger = logging.get_logger(__name__)
-
-
 def _quantization_type(weight):
     from torchao.dtypes import AffineQuantizedTensor
     from torchao.quantization.linear_activation_quantized_tensor import LinearActivationQuantizedTensor

tests/conftest.py

@@ -32,6 +32,21 @@ warnings.simplefilter(action="ignore", category=FutureWarning)
 
 def pytest_configure(config):
     config.addinivalue_line("markers", "big_accelerator: marks tests as requiring big accelerator resources")
+    config.addinivalue_line("markers", "lora: marks tests for LoRA/PEFT functionality")
+    config.addinivalue_line("markers", "ip_adapter: marks tests for IP Adapter functionality")
+    config.addinivalue_line("markers", "training: marks tests for training functionality")
+    config.addinivalue_line("markers", "attention: marks tests for attention processor functionality")
+    config.addinivalue_line("markers", "memory: marks tests for memory optimization functionality")
+    config.addinivalue_line("markers", "cpu_offload: marks tests for CPU offloading functionality")
+    config.addinivalue_line("markers", "group_offload: marks tests for group offloading functionality")
+    config.addinivalue_line("markers", "compile: marks tests for torch.compile functionality")
+    config.addinivalue_line("markers", "single_file: marks tests for single file checkpoint loading")
+    config.addinivalue_line("markers", "bitsandbytes: marks tests for BitsAndBytes quantization functionality")
+    config.addinivalue_line("markers", "quanto: marks tests for Quanto quantization functionality")
+    config.addinivalue_line("markers", "torchao: marks tests for TorchAO quantization functionality")
+    config.addinivalue_line("markers", "gguf: marks tests for GGUF quantization functionality")
+    config.addinivalue_line("markers", "modelopt: marks tests for NVIDIA ModelOpt quantization functionality")
+    config.addinivalue_line("markers", "context_parallel: marks tests for context parallel inference functionality")
 
 
 def pytest_addoption(parser):

tests/models/testing_utils/__init__.py

@@ -0,0 +1,79 @@
+from .attention import AttentionTesterMixin
+from .cache import (
+    CacheTesterMixin,
+    FasterCacheConfigMixin,
+    FasterCacheTesterMixin,
+    FirstBlockCacheConfigMixin,
+    FirstBlockCacheTesterMixin,
+    PyramidAttentionBroadcastConfigMixin,
+    PyramidAttentionBroadcastTesterMixin,
+)
+from .common import BaseModelTesterConfig, ModelTesterMixin
+from .compile import TorchCompileTesterMixin
+from .ip_adapter import IPAdapterTesterMixin
+from .lora import LoraHotSwappingForModelTesterMixin, LoraTesterMixin
+from .memory import CPUOffloadTesterMixin, GroupOffloadTesterMixin, LayerwiseCastingTesterMixin, MemoryTesterMixin
+from .parallelism import ContextParallelTesterMixin
+from .quantization import (
+    BitsAndBytesCompileTesterMixin,
+    BitsAndBytesConfigMixin,
+    BitsAndBytesTesterMixin,
+    GGUFCompileTesterMixin,
+    GGUFConfigMixin,
+    GGUFTesterMixin,
+    ModelOptCompileTesterMixin,
+    ModelOptConfigMixin,
+    ModelOptTesterMixin,
+    QuantizationCompileTesterMixin,
+    QuantizationTesterMixin,
+    QuantoCompileTesterMixin,
+    QuantoConfigMixin,
+    QuantoTesterMixin,
+    TorchAoCompileTesterMixin,
+    TorchAoConfigMixin,
+    TorchAoTesterMixin,
+)
+from .single_file import SingleFileTesterMixin
+from .training import TrainingTesterMixin
+
+
+__all__ = [
+    "AttentionTesterMixin",
+    "BaseModelTesterConfig",
+    "BitsAndBytesCompileTesterMixin",
+    "BitsAndBytesConfigMixin",
+    "BitsAndBytesTesterMixin",
+    "CacheTesterMixin",
+    "ContextParallelTesterMixin",
+    "CPUOffloadTesterMixin",
+    "FasterCacheConfigMixin",
+    "FasterCacheTesterMixin",
+    "FirstBlockCacheConfigMixin",
+    "FirstBlockCacheTesterMixin",
+    "GGUFCompileTesterMixin",
+    "GGUFConfigMixin",
+    "GGUFTesterMixin",
+    "GroupOffloadTesterMixin",
+    "IPAdapterTesterMixin",
+    "LayerwiseCastingTesterMixin",
+    "LoraHotSwappingForModelTesterMixin",
+    "LoraTesterMixin",
+    "MemoryTesterMixin",
+    "ModelOptCompileTesterMixin",
+    "ModelOptConfigMixin",
+    "ModelOptTesterMixin",
+    "ModelTesterMixin",
+    "PyramidAttentionBroadcastConfigMixin",
+    "PyramidAttentionBroadcastTesterMixin",
+    "QuantizationCompileTesterMixin",
+    "QuantizationTesterMixin",
+    "QuantoCompileTesterMixin",
+    "QuantoConfigMixin",
+    "QuantoTesterMixin",
+    "SingleFileTesterMixin",
+    "TorchAoCompileTesterMixin",
+    "TorchAoConfigMixin",
+    "TorchAoTesterMixin",
+    "TorchCompileTesterMixin",
+    "TrainingTesterMixin",
+]

tests/models/testing_utils/attention.py

@@ -0,0 +1,185 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+import torch
+
+from diffusers.models.attention import AttentionModuleMixin
+from diffusers.models.attention_processor import (
+    AttnProcessor,
+)
+
+from ...testing_utils import (
+    assert_tensors_close,
+    is_attention,
+    torch_device,
+)
+
+
+@is_attention
+class AttentionTesterMixin:
+    """
+    Mixin class for testing attention processor and module functionality on models.
+
+    Tests functionality from AttentionModuleMixin including:
+        - Attention processor management (set/get)
+        - QKV projection fusion/unfusion
+        - Attention backends (XFormers, NPU, etc.)
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+        - base_precision: Tolerance for floating point comparisons (default: 1e-3)
+        - uses_custom_attn_processor: Whether model uses custom attention processors (default: False)
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: attention
+        Use `pytest -m "not attention"` to skip these tests
+    """
+
+    base_precision = 1e-3
+
+    def test_fuse_unfuse_qkv_projections(self):
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict)
+        model.to(torch_device)
+        model.eval()
+
+        if not hasattr(model, "fuse_qkv_projections"):
+            pytest.skip("Model does not support QKV projection fusion.")
+
+        # Get output before fusion
+        with torch.no_grad():
+            output_before_fusion = model(**inputs_dict, return_dict=False)[0]
+
+        # Fuse projections
+        model.fuse_qkv_projections()
+
+        # Verify fusion occurred by checking for fused attributes
+        has_fused_projections = False
+        for module in model.modules():
+            if isinstance(module, AttentionModuleMixin):
+                if hasattr(module, "to_qkv") or hasattr(module, "to_kv"):
+                    has_fused_projections = True
+                    assert module.fused_projections, "fused_projections flag should be True"
+                    break
+
+        if has_fused_projections:
+            # Get output after fusion
+            with torch.no_grad():
+                output_after_fusion = model(**inputs_dict, return_dict=False)[0]
+
+            # Verify outputs match
+            assert_tensors_close(
+                output_before_fusion,
+                output_after_fusion,
+                atol=self.base_precision,
+                rtol=0,
+                msg="Output should not change after fusing projections",
+            )
+
+            # Unfuse projections
+            model.unfuse_qkv_projections()
+
+            # Verify unfusion occurred
+            for module in model.modules():
+                if isinstance(module, AttentionModuleMixin):
+                    assert not hasattr(module, "to_qkv"), "to_qkv should be removed after unfusing"
+                    assert not hasattr(module, "to_kv"), "to_kv should be removed after unfusing"
+                    assert not module.fused_projections, "fused_projections flag should be False"
+
+            # Get output after unfusion
+            with torch.no_grad():
+                output_after_unfusion = model(**inputs_dict, return_dict=False)[0]
+
+            # Verify outputs still match
+            assert_tensors_close(
+                output_before_fusion,
+                output_after_unfusion,
+                atol=self.base_precision,
+                rtol=0,
+                msg="Output should match original after unfusing projections",
+            )
+
+    def test_get_set_processor(self):
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict)
+        model.to(torch_device)
+
+        # Check if model has attention processors
+        if not hasattr(model, "attn_processors"):
+            pytest.skip("Model does not have attention processors.")
+
+        # Test getting processors
+        processors = model.attn_processors
+        assert isinstance(processors, dict), "attn_processors should return a dict"
+        assert len(processors) > 0, "Model should have at least one attention processor"
+
+        # Test that all processors can be retrieved via get_processor
+        for module in model.modules():
+            if isinstance(module, AttentionModuleMixin):
+                processor = module.get_processor()
+                assert processor is not None, "get_processor should return a processor"
+
+                # Test setting a new processor
+                new_processor = AttnProcessor()
+                module.set_processor(new_processor)
+                retrieved_processor = module.get_processor()
+                assert retrieved_processor is new_processor, "Retrieved processor should be the same as the one set"
+
+    def test_attention_processor_dict(self):
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict)
+        model.to(torch_device)
+
+        if not hasattr(model, "set_attn_processor"):
+            pytest.skip("Model does not support setting attention processors.")
+
+        # Get current processors
+        current_processors = model.attn_processors
+
+        # Create a dict of new processors
+        new_processors = {key: AttnProcessor() for key in current_processors.keys()}
+
+        # Set processors using dict
+        model.set_attn_processor(new_processors)
+
+        # Verify all processors were set
+        updated_processors = model.attn_processors
+        for key in current_processors.keys():
+            assert type(updated_processors[key]) == AttnProcessor, f"Processor {key} should be AttnProcessor"
+
+    def test_attention_processor_count_mismatch_raises_error(self):
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict)
+        model.to(torch_device)
+
+        if not hasattr(model, "set_attn_processor"):
+            pytest.skip("Model does not support setting attention processors.")
+
+        # Get current processors
+        current_processors = model.attn_processors
+
+        # Create a dict with wrong number of processors
+        wrong_processors = {list(current_processors.keys())[0]: AttnProcessor()}
+
+        # Verify error is raised
+        with pytest.raises(ValueError) as exc_info:
+            model.set_attn_processor(wrong_processors)
+
+        assert "number of processors" in str(exc_info.value).lower(), "Error should mention processor count mismatch"

tests/models/testing_utils/cache.py

@@ -0,0 +1,536 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import gc
+
+import pytest
+import torch
+
+from diffusers.hooks import FasterCacheConfig, FirstBlockCacheConfig, PyramidAttentionBroadcastConfig
+from diffusers.hooks.faster_cache import _FASTER_CACHE_BLOCK_HOOK, _FASTER_CACHE_DENOISER_HOOK
+from diffusers.hooks.first_block_cache import _FBC_BLOCK_HOOK, _FBC_LEADER_BLOCK_HOOK
+from diffusers.hooks.pyramid_attention_broadcast import _PYRAMID_ATTENTION_BROADCAST_HOOK
+from diffusers.models.cache_utils import CacheMixin
+
+from ...testing_utils import backend_empty_cache, is_cache, torch_device
+
+
+def require_cache_mixin(func):
+    """Decorator to skip tests if model doesn't use CacheMixin."""
+
+    def wrapper(self, *args, **kwargs):
+        if not issubclass(self.model_class, CacheMixin):
+            pytest.skip(f"{self.model_class.__name__} does not use CacheMixin.")
+        return func(self, *args, **kwargs)
+
+    return wrapper
+
+
+class CacheTesterMixin:
+    """
+    Base mixin class providing common test implementations for cache testing.
+
+    Cache-specific mixins should:
+    1. Inherit from their respective config mixin (e.g., PyramidAttentionBroadcastConfigMixin)
+    2. Inherit from this mixin
+    3. Define the cache config to use for tests
+
+    Expected class attributes:
+        - model_class: The model class to test (must use CacheMixin)
+
+    Expected methods in test classes:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+    """
+
+    def setup_method(self):
+        gc.collect()
+        backend_empty_cache(torch_device)
+
+    def teardown_method(self):
+        gc.collect()
+        backend_empty_cache(torch_device)
+
+    def _get_cache_config(self):
+        """
+        Get the cache config for testing.
+        Should be implemented by subclasses.
+        """
+        raise NotImplementedError("Subclass must implement _get_cache_config")
+
+    def _get_hook_names(self):
+        """
+        Get the hook names to check for this cache type.
+        Should be implemented by subclasses.
+        Returns a list of hook name strings.
+        """
+        raise NotImplementedError("Subclass must implement _get_hook_names")
+
+    def _test_cache_enable_disable_state(self):
+        """Test that cache enable/disable updates the is_cache_enabled state correctly."""
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        # Initially cache should not be enabled
+        assert not model.is_cache_enabled, "Cache should not be enabled initially."
+
+        config = self._get_cache_config()
+
+        # Enable cache
+        model.enable_cache(config)
+        assert model.is_cache_enabled, "Cache should be enabled after enable_cache()."
+
+        # Disable cache
+        model.disable_cache()
+        assert not model.is_cache_enabled, "Cache should not be enabled after disable_cache()."
+
+    def _test_cache_double_enable_raises_error(self):
+        """Test that enabling cache twice raises an error."""
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        config = self._get_cache_config()
+
+        model.enable_cache(config)
+
+        # Trying to enable again should raise ValueError
+        with pytest.raises(ValueError, match="Caching has already been enabled"):
+            model.enable_cache(config)
+
+        # Cleanup
+        model.disable_cache()
+
+    def _test_cache_hooks_registered(self):
+        """Test that cache hooks are properly registered and removed."""
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        config = self._get_cache_config()
+        hook_names = self._get_hook_names()
+
+        model.enable_cache(config)
+
+        # Check that at least one hook was registered
+        hook_count = 0
+        for module in model.modules():
+            if hasattr(module, "_diffusers_hook"):
+                for hook_name in hook_names:
+                    hook = module._diffusers_hook.get_hook(hook_name)
+                    if hook is not None:
+                        hook_count += 1
+
+        assert hook_count > 0, f"At least one cache hook should be registered. Hook names: {hook_names}"
+
+        # Disable and verify hooks are removed
+        model.disable_cache()
+
+        hook_count_after = 0
+        for module in model.modules():
+            if hasattr(module, "_diffusers_hook"):
+                for hook_name in hook_names:
+                    hook = module._diffusers_hook.get_hook(hook_name)
+                    if hook is not None:
+                        hook_count_after += 1
+
+        assert hook_count_after == 0, "Cache hooks should be removed after disable_cache()."
+
+    @torch.no_grad()
+    def _test_cache_inference(self):
+        """Test that model can run inference with cache enabled."""
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+
+        config = self._get_cache_config()
+
+        model.enable_cache(config)
+
+        # First pass populates the cache
+        _ = model(**inputs_dict, return_dict=False)[0]
+
+        # Create modified inputs for second pass (vary hidden_states to simulate denoising)
+        inputs_dict_step2 = inputs_dict.copy()
+        if "hidden_states" in inputs_dict_step2:
+            inputs_dict_step2["hidden_states"] = inputs_dict_step2["hidden_states"] + 0.1
+
+        # Second pass uses cached attention with different hidden_states (produces approximated output)
+        output_with_cache = model(**inputs_dict_step2, return_dict=False)[0]
+
+        assert output_with_cache is not None, "Model output should not be None with cache enabled."
+        assert not torch.isnan(output_with_cache).any(), "Model output contains NaN with cache enabled."
+
+        # Run same inputs without cache to compare
+        model.disable_cache()
+        output_without_cache = model(**inputs_dict_step2, return_dict=False)[0]
+
+        # Cached output should be different from non-cached output (due to approximation)
+        assert not torch.allclose(output_without_cache, output_with_cache, atol=1e-5), (
+            "Cached output should be different from non-cached output due to cache approximation."
+        )
+
+    def _test_cache_context_manager(self):
+        """Test the cache_context context manager."""
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        config = self._get_cache_config()
+
+        model.enable_cache(config)
+
+        # Test cache_context works without error
+        with model.cache_context("test_context"):
+            pass
+
+        model.disable_cache()
+
+    def _test_reset_stateful_cache(self):
+        """Test that _reset_stateful_cache resets the cache state."""
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+
+        config = self._get_cache_config()
+
+        model.enable_cache(config)
+
+        # Run forward to populate cache state
+        with torch.no_grad():
+            _ = model(**inputs_dict, return_dict=False)[0]
+
+        # Reset should not raise any errors
+        model._reset_stateful_cache()
+
+        model.disable_cache()
+
+
+@is_cache
+class PyramidAttentionBroadcastConfigMixin:
+    """
+    Base mixin providing PyramidAttentionBroadcast cache config.
+
+    Expected class attributes:
+        - model_class: The model class to test (must use CacheMixin)
+    """
+
+    # Default PAB config - can be overridden by subclasses
+    PAB_CONFIG = {
+        "spatial_attention_block_skip_range": 2,
+    }
+
+    # Store timestep for callback (must be within default range (100, 800) for skipping to trigger)
+    _current_timestep = 500
+
+    def _get_cache_config(self):
+        config_kwargs = self.PAB_CONFIG.copy()
+        config_kwargs["current_timestep_callback"] = lambda: self._current_timestep
+        return PyramidAttentionBroadcastConfig(**config_kwargs)
+
+    def _get_hook_names(self):
+        return [_PYRAMID_ATTENTION_BROADCAST_HOOK]
+
+
+@is_cache
+class PyramidAttentionBroadcastTesterMixin(PyramidAttentionBroadcastConfigMixin, CacheTesterMixin):
+    """
+    Mixin class for testing PyramidAttentionBroadcast caching on models.
+
+    Expected class attributes:
+        - model_class: The model class to test (must use CacheMixin)
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: cache
+        Use `pytest -m "not cache"` to skip these tests
+    """
+
+    @require_cache_mixin
+    def test_pab_cache_enable_disable_state(self):
+        self._test_cache_enable_disable_state()
+
+    @require_cache_mixin
+    def test_pab_cache_double_enable_raises_error(self):
+        self._test_cache_double_enable_raises_error()
+
+    @require_cache_mixin
+    def test_pab_cache_hooks_registered(self):
+        self._test_cache_hooks_registered()
+
+    @require_cache_mixin
+    def test_pab_cache_inference(self):
+        self._test_cache_inference()
+
+    @require_cache_mixin
+    def test_pab_cache_context_manager(self):
+        self._test_cache_context_manager()
+
+    @require_cache_mixin
+    def test_pab_reset_stateful_cache(self):
+        self._test_reset_stateful_cache()
+
+
+@is_cache
+class FirstBlockCacheConfigMixin:
+    """
+    Base mixin providing FirstBlockCache config.
+
+    Expected class attributes:
+        - model_class: The model class to test (must use CacheMixin)
+    """
+
+    # Default FBC config - can be overridden by subclasses
+    # Higher threshold makes FBC more aggressive about caching (skips more often)
+    FBC_CONFIG = {
+        "threshold": 1.0,
+    }
+
+    def _get_cache_config(self):
+        return FirstBlockCacheConfig(**self.FBC_CONFIG)
+
+    def _get_hook_names(self):
+        return [_FBC_LEADER_BLOCK_HOOK, _FBC_BLOCK_HOOK]
+
+
+@is_cache
+class FirstBlockCacheTesterMixin(FirstBlockCacheConfigMixin, CacheTesterMixin):
+    """
+    Mixin class for testing FirstBlockCache on models.
+
+    Expected class attributes:
+        - model_class: The model class to test (must use CacheMixin)
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: cache
+        Use `pytest -m "not cache"` to skip these tests
+    """
+
+    @torch.no_grad()
+    def _test_cache_inference(self):
+        """Test that model can run inference with FBC cache enabled (requires cache_context)."""
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+
+        config = self._get_cache_config()
+        model.enable_cache(config)
+
+        # FBC requires cache_context to be set for inference
+        with model.cache_context("fbc_test"):
+            # First pass populates the cache
+            _ = model(**inputs_dict, return_dict=False)[0]
+
+            # Create modified inputs for second pass (small perturbation keeps residuals similar)
+            inputs_dict_step2 = inputs_dict.copy()
+            if "hidden_states" in inputs_dict_step2:
+                inputs_dict_step2["hidden_states"] = inputs_dict_step2["hidden_states"] + 0.01
+
+            # Second pass - FBC should skip remaining blocks and use cached residuals
+            output_with_cache = model(**inputs_dict_step2, return_dict=False)[0]
+
+        assert output_with_cache is not None, "Model output should not be None with cache enabled."
+        assert not torch.isnan(output_with_cache).any(), "Model output contains NaN with cache enabled."
+
+        # Run same inputs without cache to compare
+        model.disable_cache()
+        output_without_cache = model(**inputs_dict_step2, return_dict=False)[0]
+
+        # Cached output should be different from non-cached output (due to approximation)
+        assert not torch.allclose(output_without_cache, output_with_cache, atol=1e-5), (
+            "Cached output should be different from non-cached output due to cache approximation."
+        )
+
+    def _test_reset_stateful_cache(self):
+        """Test that _reset_stateful_cache resets the FBC cache state (requires cache_context)."""
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+
+        config = self._get_cache_config()
+        model.enable_cache(config)
+
+        # FBC requires cache_context to be set for inference
+        with model.cache_context("fbc_test"):
+            with torch.no_grad():
+                _ = model(**inputs_dict, return_dict=False)[0]
+
+        # Reset should not raise any errors
+        model._reset_stateful_cache()
+
+        model.disable_cache()
+
+    @require_cache_mixin
+    def test_fbc_cache_enable_disable_state(self):
+        self._test_cache_enable_disable_state()
+
+    @require_cache_mixin
+    def test_fbc_cache_double_enable_raises_error(self):
+        self._test_cache_double_enable_raises_error()
+
+    @require_cache_mixin
+    def test_fbc_cache_hooks_registered(self):
+        self._test_cache_hooks_registered()
+
+    @require_cache_mixin
+    def test_fbc_cache_inference(self):
+        self._test_cache_inference()
+
+    @require_cache_mixin
+    def test_fbc_cache_context_manager(self):
+        self._test_cache_context_manager()
+
+    @require_cache_mixin
+    def test_fbc_reset_stateful_cache(self):
+        self._test_reset_stateful_cache()
+
+
+@is_cache
+class FasterCacheConfigMixin:
+    """
+    Base mixin providing FasterCache config.
+
+    Expected class attributes:
+        - model_class: The model class to test (must use CacheMixin)
+    """
+
+    # Default FasterCache config - can be overridden by subclasses
+    FASTER_CACHE_CONFIG = {
+        "spatial_attention_block_skip_range": 2,
+        "spatial_attention_timestep_skip_range": (-1, 901),
+        "tensor_format": "BCHW",
+    }
+
+    # Store timestep for callback - use a list so it can be mutated during test
+    # Starts outside skip range so first pass computes; changed to inside range for subsequent passes
+    _current_timestep = [1000]
+
+    def _get_cache_config(self):
+        config_kwargs = self.FASTER_CACHE_CONFIG.copy()
+        config_kwargs["current_timestep_callback"] = lambda: self._current_timestep[0]
+        return FasterCacheConfig(**config_kwargs)
+
+    def _get_hook_names(self):
+        return [_FASTER_CACHE_DENOISER_HOOK, _FASTER_CACHE_BLOCK_HOOK]
+
+
+@is_cache
+class FasterCacheTesterMixin(FasterCacheConfigMixin, CacheTesterMixin):
+    """
+    Mixin class for testing FasterCache on models.
+
+    Note: FasterCache is designed for pipeline-level inference with proper CFG batch handling
+    and timestep management. Inference tests are skipped at model level - FasterCache should
+    be tested via pipeline tests (e.g., FluxPipeline, HunyuanVideoPipeline).
+
+    Expected class attributes:
+        - model_class: The model class to test (must use CacheMixin)
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: cache
+        Use `pytest -m "not cache"` to skip these tests
+    """
+
+    @torch.no_grad()
+    def _test_cache_inference(self):
+        """Test that model can run inference with FasterCache enabled."""
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+
+        config = self._get_cache_config()
+
+        model.enable_cache(config)
+
+        # First pass with timestep outside skip range - computes and populates cache
+        self._current_timestep[0] = 1000
+        _ = model(**inputs_dict, return_dict=False)[0]
+
+        # Move timestep inside skip range so subsequent passes use cache
+        self._current_timestep[0] = 500
+
+        # Create modified inputs for second pass
+        inputs_dict_step2 = inputs_dict.copy()
+        if "hidden_states" in inputs_dict_step2:
+            inputs_dict_step2["hidden_states"] = inputs_dict_step2["hidden_states"] + 0.1
+
+        # Second pass uses cached attention with different hidden_states
+        output_with_cache = model(**inputs_dict_step2, return_dict=False)[0]
+
+        assert output_with_cache is not None, "Model output should not be None with cache enabled."
+        assert not torch.isnan(output_with_cache).any(), "Model output contains NaN with cache enabled."
+
+        # Run same inputs without cache to compare
+        model.disable_cache()
+        output_without_cache = model(**inputs_dict_step2, return_dict=False)[0]
+
+        # Cached output should be different from non-cached output (due to approximation)
+        assert not torch.allclose(output_without_cache, output_with_cache, atol=1e-5), (
+            "Cached output should be different from non-cached output due to cache approximation."
+        )
+
+    def _test_reset_stateful_cache(self):
+        """Test that _reset_stateful_cache resets the FasterCache state."""
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+
+        config = self._get_cache_config()
+        model.enable_cache(config)
+
+        # First pass with timestep outside skip range
+        self._current_timestep[0] = 1000
+        with torch.no_grad():
+            _ = model(**inputs_dict, return_dict=False)[0]
+
+        # Reset should not raise any errors
+        model._reset_stateful_cache()
+
+        model.disable_cache()
+
+    @require_cache_mixin
+    def test_faster_cache_enable_disable_state(self):
+        self._test_cache_enable_disable_state()
+
+    @require_cache_mixin
+    def test_faster_cache_double_enable_raises_error(self):
+        self._test_cache_double_enable_raises_error()
+
+    @require_cache_mixin
+    def test_faster_cache_hooks_registered(self):
+        self._test_cache_hooks_registered()
+
+    @require_cache_mixin
+    def test_faster_cache_inference(self):
+        self._test_cache_inference()
+
+    @require_cache_mixin
+    def test_faster_cache_context_manager(self):
+        self._test_cache_context_manager()
+
+    @require_cache_mixin
+    def test_faster_cache_reset_stateful_cache(self):
+        self._test_reset_stateful_cache()

tests/models/testing_utils/common.py

@@ -0,0 +1,649 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import json
+import os
+from collections import defaultdict
+from typing import Any, Dict, Optional, Type
+
+import pytest
+import torch
+import torch.nn as nn
+from accelerate.utils.modeling import _get_proper_dtype, compute_module_sizes, dtype_byte_size
+
+from diffusers.utils import SAFE_WEIGHTS_INDEX_NAME, _add_variant, logging
+from diffusers.utils.testing_utils import require_accelerator, require_torch_multi_accelerator
+
+from ...testing_utils import assert_tensors_close, torch_device
+
+
+def named_persistent_module_tensors(
+    module: nn.Module,
+    recurse: bool = False,
+):
+    """
+    A helper function that gathers all the tensors (parameters + persistent buffers) of a given module.
+
+    Args:
+        module (`torch.nn.Module`):
+            The module we want the tensors on.
+        recurse (`bool`, *optional`, defaults to `False`):
+            Whether or not to go look in every submodule or just return the direct parameters and buffers.
+    """
+    yield from module.named_parameters(recurse=recurse)
+
+    for named_buffer in module.named_buffers(recurse=recurse):
+        name, _ = named_buffer
+        # Get parent by splitting on dots and traversing the model
+        parent = module
+        if "." in name:
+            parent_name = name.rsplit(".", 1)[0]
+            for part in parent_name.split("."):
+                parent = getattr(parent, part)
+            name = name.split(".")[-1]
+        if name not in parent._non_persistent_buffers_set:
+            yield named_buffer
+
+
+def compute_module_persistent_sizes(
+    model: nn.Module,
+    dtype: str | torch.device | None = None,
+    special_dtypes: dict[str, str | torch.device] | None = None,
+):
+    """
+    Compute the size of each submodule of a given model (parameters + persistent buffers).
+    """
+    if dtype is not None:
+        dtype = _get_proper_dtype(dtype)
+        dtype_size = dtype_byte_size(dtype)
+    if special_dtypes is not None:
+        special_dtypes = {key: _get_proper_dtype(dtyp) for key, dtyp in special_dtypes.items()}
+        special_dtypes_size = {key: dtype_byte_size(dtyp) for key, dtyp in special_dtypes.items()}
+    module_sizes = defaultdict(int)
+
+    module_list = []
+
+    module_list = named_persistent_module_tensors(model, recurse=True)
+
+    for name, tensor in module_list:
+        if special_dtypes is not None and name in special_dtypes:
+            size = tensor.numel() * special_dtypes_size[name]
+        elif dtype is None:
+            size = tensor.numel() * dtype_byte_size(tensor.dtype)
+        elif str(tensor.dtype).startswith(("torch.uint", "torch.int", "torch.bool")):
+            # According to the code in set_module_tensor_to_device, these types won't be converted
+            # so use their original size here
+            size = tensor.numel() * dtype_byte_size(tensor.dtype)
+        else:
+            size = tensor.numel() * min(dtype_size, dtype_byte_size(tensor.dtype))
+        name_parts = name.split(".")
+        for idx in range(len(name_parts) + 1):
+            module_sizes[".".join(name_parts[:idx])] += size
+
+    return module_sizes
+
+
+def calculate_expected_num_shards(index_map_path):
+    """
+    Calculate expected number of shards from index file.
+
+    Args:
+        index_map_path: Path to the sharded checkpoint index file
+
+    Returns:
+        int: Expected number of shards
+    """
+    with open(index_map_path) as f:
+        weight_map_dict = json.load(f)["weight_map"]
+    first_key = list(weight_map_dict.keys())[0]
+    weight_loc = weight_map_dict[first_key]  # e.g., diffusion_pytorch_model-00001-of-00002.safetensors
+    expected_num_shards = int(weight_loc.split("-")[-1].split(".")[0])
+    return expected_num_shards
+
+
+def check_device_map_is_respected(model, device_map):
+    for param_name, param in model.named_parameters():
+        # Find device in device_map
+        while len(param_name) > 0 and param_name not in device_map:
+            param_name = ".".join(param_name.split(".")[:-1])
+        if param_name not in device_map:
+            raise ValueError("device map is incomplete, it does not contain any device for `param_name`.")
+
+        param_device = device_map[param_name]
+        if param_device in ["cpu", "disk"]:
+            assert param.device == torch.device("meta"), f"Expected device 'meta' for {param_name}, got {param.device}"
+        else:
+            assert param.device == torch.device(param_device), (
+                f"Expected device {param_device} for {param_name}, got {param.device}"
+            )
+
+
+class BaseModelTesterConfig:
+    """
+    Base class defining the configuration interface for model testing.
+
+    This class defines the contract that all model test classes must implement.
+    It provides a consistent interface for accessing model configuration, initialization
+    parameters, and test inputs across all testing mixins.
+
+    Required properties (must be implemented by subclasses):
+        - model_class: The model class to test
+
+    Optional properties (can be overridden, have sensible defaults):
+        - pretrained_model_name_or_path: Hub repository ID for pretrained model (default: None)
+        - pretrained_model_kwargs: Additional kwargs for from_pretrained (default: {})
+        - output_shape: Expected output shape for output validation tests (default: None)
+        - base_precision: Default tolerance for floating point comparisons (default: 1e-3)
+        - model_split_percents: Percentages for model parallelism tests (default: [0.5, 0.7])
+
+    Required methods (must be implemented by subclasses):
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Example usage:
+        class MyModelTestConfig(BaseModelTesterConfig):
+            @property
+            def model_class(self):
+                return MyModel
+
+            @property
+            def pretrained_model_name_or_path(self):
+                return "org/my-model"
+
+            @property
+            def output_shape(self):
+                return (1, 3, 32, 32)
+
+            def get_init_dict(self):
+                return {"in_channels": 3, "out_channels": 3}
+
+            def get_dummy_inputs(self):
+                return {"sample": torch.randn(1, 3, 32, 32, device=torch_device)}
+
+        class TestMyModel(MyModelTestConfig, ModelTesterMixin, QuantizationTesterMixin):
+            pass
+    """
+
+    # ==================== Required Properties ====================
+
+    @property
+    def model_class(self) -> Type[nn.Module]:
+        """The model class to test. Must be implemented by subclasses."""
+        raise NotImplementedError("Subclasses must implement the `model_class` property.")
+
+    # ==================== Optional Properties ====================
+
+    @property
+    def pretrained_model_name_or_path(self) -> Optional[str]:
+        """Hub repository ID for the pretrained model (used for quantization and hub tests)."""
+        return None
+
+    @property
+    def pretrained_model_kwargs(self) -> Dict[str, Any]:
+        """Additional kwargs to pass to from_pretrained (e.g., subfolder, variant)."""
+        return {}
+
+    @property
+    def output_shape(self) -> Optional[tuple]:
+        """Expected output shape for output validation tests."""
+        return None
+
+    @property
+    def model_split_percents(self) -> list:
+        """Percentages for model parallelism tests."""
+        return [0.5, 0.7]
+
+    # ==================== Required Methods ====================
+
+    def get_init_dict(self) -> Dict[str, Any]:
+        """
+        Returns dict of arguments to initialize the model.
+
+        Returns:
+            Dict[str, Any]: Initialization arguments for the model constructor.
+
+        Example:
+            return {
+                "in_channels": 3,
+                "out_channels": 3,
+                "sample_size": 32,
+            }
+        """
+        raise NotImplementedError("Subclasses must implement `get_init_dict()`.")
+
+    def get_dummy_inputs(self) -> Dict[str, Any]:
+        """
+        Returns dict of inputs to pass to the model forward pass.
+
+        Returns:
+            Dict[str, Any]: Input tensors/values for model.forward().
+
+        Example:
+            return {
+                "sample": torch.randn(1, 3, 32, 32, device=torch_device),
+                "timestep": torch.tensor([1], device=torch_device),
+            }
+        """
+        raise NotImplementedError("Subclasses must implement `get_dummy_inputs()`.")
+
+
+class ModelTesterMixin:
+    """
+    Base mixin class for model testing with common test methods.
+
+    This mixin expects the test class to also inherit from BaseModelTesterConfig
+    (or implement its interface) which provides:
+        - model_class: The model class to test
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Example:
+        class MyModelTestConfig(BaseModelTesterConfig):
+            model_class = MyModel
+            def get_init_dict(self): ...
+            def get_dummy_inputs(self): ...
+
+        class TestMyModel(MyModelTestConfig, ModelTesterMixin):
+            pass
+    """
+
+    def test_from_save_pretrained(self, tmp_path, atol=5e-5, rtol=5e-5):
+        torch.manual_seed(0)
+        model = self.model_class(**self.get_init_dict())
+        model.to(torch_device)
+        model.eval()
+
+        model.save_pretrained(tmp_path)
+        new_model = self.model_class.from_pretrained(tmp_path)
+        new_model.to(torch_device)
+
+        # check if all parameters shape are the same
+        for param_name in model.state_dict().keys():
+            param_1 = model.state_dict()[param_name]
+            param_2 = new_model.state_dict()[param_name]
+            assert param_1.shape == param_2.shape, (
+                f"Parameter shape mismatch for {param_name}. Original: {param_1.shape}, loaded: {param_2.shape}"
+            )
+
+        with torch.no_grad():
+            image = model(**self.get_dummy_inputs(), return_dict=False)[0]
+            new_image = new_model(**self.get_dummy_inputs(), return_dict=False)[0]
+
+        assert_tensors_close(image, new_image, atol=atol, rtol=rtol, msg="Models give different forward passes.")
+
+    def test_from_save_pretrained_variant(self, tmp_path, atol=5e-5, rtol=0):
+        model = self.model_class(**self.get_init_dict())
+        model.to(torch_device)
+        model.eval()
+
+        model.save_pretrained(tmp_path, variant="fp16")
+        new_model = self.model_class.from_pretrained(tmp_path, variant="fp16")
+
+        # non-variant cannot be loaded
+        with pytest.raises(OSError) as exc_info:
+            self.model_class.from_pretrained(tmp_path)
+
+        # make sure that error message states what keys are missing
+        assert "Error no file named diffusion_pytorch_model.bin found in directory" in str(exc_info.value)
+
+        new_model.to(torch_device)
+
+        with torch.no_grad():
+            image = model(**self.get_dummy_inputs(), return_dict=False)[0]
+            new_image = new_model(**self.get_dummy_inputs(), return_dict=False)[0]
+
+        assert_tensors_close(image, new_image, atol=atol, rtol=rtol, msg="Models give different forward passes.")
+
+    @pytest.mark.parametrize("dtype", [torch.float32, torch.float16, torch.bfloat16], ids=["fp32", "fp16", "bf16"])
+    def test_from_save_pretrained_dtype(self, tmp_path, dtype):
+        model = self.model_class(**self.get_init_dict())
+        model.to(torch_device)
+        model.eval()
+
+        if torch_device == "mps" and dtype == torch.bfloat16:
+            pytest.skip(reason=f"{dtype} is not supported on {torch_device}")
+
+        model.to(dtype)
+        model.save_pretrained(tmp_path)
+        new_model = self.model_class.from_pretrained(tmp_path, low_cpu_mem_usage=True, torch_dtype=dtype)
+        assert new_model.dtype == dtype
+        if hasattr(self.model_class, "_keep_in_fp32_modules") and self.model_class._keep_in_fp32_modules is None:
+            # When loading without accelerate dtype == torch.float32 if _keep_in_fp32_modules is not None
+            new_model = self.model_class.from_pretrained(tmp_path, low_cpu_mem_usage=False, torch_dtype=dtype)
+            assert new_model.dtype == dtype
+
+    def test_determinism(self, atol=1e-5, rtol=0):
+        model = self.model_class(**self.get_init_dict())
+        model.to(torch_device)
+        model.eval()
+
+        with torch.no_grad():
+            first = model(**self.get_dummy_inputs(), return_dict=False)[0]
+            second = model(**self.get_dummy_inputs(), return_dict=False)[0]
+
+        # Filter out NaN values before comparison
+        first_flat = first.flatten()
+        second_flat = second.flatten()
+        mask = ~(torch.isnan(first_flat) | torch.isnan(second_flat))
+        first_filtered = first_flat[mask]
+        second_filtered = second_flat[mask]
+
+        assert_tensors_close(
+            first_filtered, second_filtered, atol=atol, rtol=rtol, msg="Model outputs are not deterministic"
+        )
+
+    def test_output(self, expected_output_shape=None):
+        model = self.model_class(**self.get_init_dict())
+        model.to(torch_device)
+        model.eval()
+
+        inputs_dict = self.get_dummy_inputs()
+        with torch.no_grad():
+            output = model(**inputs_dict, return_dict=False)[0]
+
+        assert output is not None, "Model output is None"
+        assert output[0].shape == expected_output_shape or self.output_shape, (
+            f"Output shape does not match expected. Expected {expected_output_shape}, got {output.shape}"
+        )
+
+    def test_outputs_equivalence(self):
+        def set_nan_tensor_to_zero(t):
+            # Temporary fallback until `aten::_index_put_impl_` is implemented in mps
+            # Track progress in https://github.com/pytorch/pytorch/issues/77764
+            device = t.device
+            if device.type == "mps":
+                t = t.to("cpu")
+            t[t != t] = 0
+            return t.to(device)
+
+        def recursive_check(tuple_object, dict_object):
+            if isinstance(tuple_object, (list, tuple)):
+                for tuple_iterable_value, dict_iterable_value in zip(tuple_object, dict_object.values()):
+                    recursive_check(tuple_iterable_value, dict_iterable_value)
+            elif isinstance(tuple_object, dict):
+                for tuple_iterable_value, dict_iterable_value in zip(tuple_object.values(), dict_object.values()):
+                    recursive_check(tuple_iterable_value, dict_iterable_value)
+            elif tuple_object is None:
+                return
+            else:
+                assert_tensors_close(
+                    set_nan_tensor_to_zero(tuple_object),
+                    set_nan_tensor_to_zero(dict_object),
+                    atol=1e-5,
+                    rtol=0,
+                    msg="Tuple and dict output are not equal",
+                )
+
+        model = self.model_class(**self.get_init_dict())
+        model.to(torch_device)
+        model.eval()
+
+        with torch.no_grad():
+            outputs_dict = model(**self.get_dummy_inputs())
+            outputs_tuple = model(**self.get_dummy_inputs(), return_dict=False)
+
+        recursive_check(outputs_tuple, outputs_dict)
+
+    def test_getattr_is_correct(self, caplog):
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict)
+
+        # save some things to test
+        model.dummy_attribute = 5
+        model.register_to_config(test_attribute=5)
+
+        logger_name = "diffusers.models.modeling_utils"
+        with caplog.at_level(logging.WARNING, logger=logger_name):
+            caplog.clear()
+            assert hasattr(model, "dummy_attribute")
+            assert getattr(model, "dummy_attribute") == 5
+            assert model.dummy_attribute == 5
+
+        # no warning should be thrown
+        assert caplog.text == ""
+
+        with caplog.at_level(logging.WARNING, logger=logger_name):
+            caplog.clear()
+            assert hasattr(model, "save_pretrained")
+            fn = model.save_pretrained
+            fn_1 = getattr(model, "save_pretrained")
+
+            assert fn == fn_1
+
+        # no warning should be thrown
+        assert caplog.text == ""
+
+        # warning should be thrown for config attributes accessed directly
+        with pytest.warns(FutureWarning):
+            assert model.test_attribute == 5
+
+        with pytest.warns(FutureWarning):
+            assert getattr(model, "test_attribute") == 5
+
+        with pytest.raises(AttributeError) as error:
+            model.does_not_exist
+
+        assert str(error.value) == f"'{type(model).__name__}' object has no attribute 'does_not_exist'"
+
+    @require_accelerator
+    @pytest.mark.skipif(
+        torch_device not in ["cuda", "xpu"],
+        reason="float16 and bfloat16 can only be used with an accelerator",
+    )
+    def test_keep_in_fp32_modules(self):
+        model = self.model_class(**self.get_init_dict())
+        fp32_modules = model._keep_in_fp32_modules
+
+        if fp32_modules is None or len(fp32_modules) == 0:
+            pytest.skip("Model does not have _keep_in_fp32_modules defined.")
+
+        # Test with float16
+        model.to(torch_device)
+        model.to(torch.float16)
+
+        for name, param in model.named_parameters():
+            if any(module_to_keep_in_fp32 in name.split(".") for module_to_keep_in_fp32 in fp32_modules):
+                assert param.dtype == torch.float32, f"Parameter {name} should be float32 but got {param.dtype}"
+            else:
+                assert param.dtype == torch.float16, f"Parameter {name} should be float16 but got {param.dtype}"
+
+    @require_accelerator
+    @pytest.mark.skipif(
+        torch_device not in ["cuda", "xpu"],
+        reason="float16 and bfloat16 can only be use for inference with an accelerator",
+    )
+    @pytest.mark.parametrize("dtype", [torch.float16, torch.bfloat16], ids=["fp16", "bf16"])
+    def test_from_save_pretrained_dtype_inference(self, tmp_path, dtype):
+        model = self.model_class(**self.get_init_dict())
+        model.to(torch_device)
+        fp32_modules = model._keep_in_fp32_modules
+
+        model.to(dtype).save_pretrained(tmp_path)
+        model_loaded = self.model_class.from_pretrained(tmp_path, torch_dtype=dtype).to(torch_device)
+
+        for name, param in model_loaded.named_parameters():
+            if any(module_to_keep_in_fp32 in name.split(".") for module_to_keep_in_fp32 in fp32_modules):
+                assert param.data.dtype == torch.float32
+            else:
+                assert param.data.dtype == dtype
+
+        with torch.no_grad():
+            output = model(**self.get_dummy_inputs(), return_dict=False)[0]
+            output_loaded = model_loaded(**self.get_dummy_inputs(), return_dict=False)[0]
+
+        assert_tensors_close(output, output_loaded, atol=1e-4, rtol=0, msg=f"Loaded model output differs for {dtype}")
+
+    @require_accelerator
+    def test_sharded_checkpoints(self, tmp_path):
+        torch.manual_seed(0)
+        config = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**config).eval()
+        model = model.to(torch_device)
+
+        base_output = model(**inputs_dict, return_dict=False)[0]
+
+        model_size = compute_module_persistent_sizes(model)[""]
+        max_shard_size = int((model_size * 0.75) / (2**10))  # Convert to KB as these test models are small
+
+        model.cpu().save_pretrained(tmp_path, max_shard_size=f"{max_shard_size}KB")
+        assert os.path.exists(os.path.join(tmp_path, SAFE_WEIGHTS_INDEX_NAME)), "Index file should exist"
+
+        # Check if the right number of shards exists
+        expected_num_shards = calculate_expected_num_shards(os.path.join(tmp_path, SAFE_WEIGHTS_INDEX_NAME))
+        actual_num_shards = len([file for file in os.listdir(tmp_path) if file.endswith(".safetensors")])
+        assert actual_num_shards == expected_num_shards, (
+            f"Expected {expected_num_shards} shards, got {actual_num_shards}"
+        )
+
+        new_model = self.model_class.from_pretrained(tmp_path).eval()
+        new_model = new_model.to(torch_device)
+
+        torch.manual_seed(0)
+        inputs_dict_new = self.get_dummy_inputs()
+        new_output = new_model(**inputs_dict_new, return_dict=False)[0]
+
+        assert_tensors_close(
+            base_output, new_output, atol=1e-5, rtol=0, msg="Output should match after sharded save/load"
+        )
+
+    @require_accelerator
+    def test_sharded_checkpoints_with_variant(self, tmp_path):
+        torch.manual_seed(0)
+        config = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**config).eval()
+        model = model.to(torch_device)
+
+        base_output = model(**inputs_dict, return_dict=False)[0]
+
+        model_size = compute_module_persistent_sizes(model)[""]
+        max_shard_size = int((model_size * 0.75) / (2**10))  # Convert to KB as these test models are small
+        variant = "fp16"
+
+        model.cpu().save_pretrained(tmp_path, max_shard_size=f"{max_shard_size}KB", variant=variant)
+
+        index_filename = _add_variant(SAFE_WEIGHTS_INDEX_NAME, variant)
+        assert os.path.exists(os.path.join(tmp_path, index_filename)), (
+            f"Variant index file {index_filename} should exist"
+        )
+
+        # Check if the right number of shards exists
+        expected_num_shards = calculate_expected_num_shards(os.path.join(tmp_path, index_filename))
+        actual_num_shards = len([file for file in os.listdir(tmp_path) if file.endswith(".safetensors")])
+        assert actual_num_shards == expected_num_shards, (
+            f"Expected {expected_num_shards} shards, got {actual_num_shards}"
+        )
+
+        new_model = self.model_class.from_pretrained(tmp_path, variant=variant).eval()
+        new_model = new_model.to(torch_device)
+
+        torch.manual_seed(0)
+        inputs_dict_new = self.get_dummy_inputs()
+        new_output = new_model(**inputs_dict_new, return_dict=False)[0]
+
+        assert_tensors_close(
+            base_output, new_output, atol=1e-5, rtol=0, msg="Output should match after variant sharded save/load"
+        )
+
+    def test_sharded_checkpoints_with_parallel_loading(self, tmp_path):
+        from diffusers.utils import constants
+
+        torch.manual_seed(0)
+        config = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**config).eval()
+        model = model.to(torch_device)
+
+        base_output = model(**inputs_dict, return_dict=False)[0]
+
+        model_size = compute_module_persistent_sizes(model)[""]
+        max_shard_size = int((model_size * 0.75) / (2**10))  # Convert to KB as these test models are small
+
+        # Save original values to restore after test
+        original_parallel_loading = constants.HF_ENABLE_PARALLEL_LOADING
+        original_parallel_workers = getattr(constants, "HF_PARALLEL_WORKERS", None)
+
+        try:
+            model.cpu().save_pretrained(tmp_path, max_shard_size=f"{max_shard_size}KB")
+            assert os.path.exists(os.path.join(tmp_path, SAFE_WEIGHTS_INDEX_NAME)), "Index file should exist"
+
+            # Check if the right number of shards exists
+            expected_num_shards = calculate_expected_num_shards(os.path.join(tmp_path, SAFE_WEIGHTS_INDEX_NAME))
+            actual_num_shards = len([file for file in os.listdir(tmp_path) if file.endswith(".safetensors")])
+            assert actual_num_shards == expected_num_shards, (
+                f"Expected {expected_num_shards} shards, got {actual_num_shards}"
+            )
+
+            # Load without parallel loading
+            constants.HF_ENABLE_PARALLEL_LOADING = False
+            model_sequential = self.model_class.from_pretrained(tmp_path).eval()
+            model_sequential = model_sequential.to(torch_device)
+
+            # Load with parallel loading
+            constants.HF_ENABLE_PARALLEL_LOADING = True
+            constants.DEFAULT_HF_PARALLEL_LOADING_WORKERS = 2
+
+            torch.manual_seed(0)
+            model_parallel = self.model_class.from_pretrained(tmp_path).eval()
+            model_parallel = model_parallel.to(torch_device)
+
+            torch.manual_seed(0)
+            inputs_dict_parallel = self.get_dummy_inputs()
+            output_parallel = model_parallel(**inputs_dict_parallel, return_dict=False)[0]
+
+            assert_tensors_close(
+                base_output, output_parallel, atol=1e-5, rtol=0, msg="Output should match with parallel loading"
+            )
+
+        finally:
+            # Restore original values
+            constants.HF_ENABLE_PARALLEL_LOADING = original_parallel_loading
+            if original_parallel_workers is not None:
+                constants.HF_PARALLEL_WORKERS = original_parallel_workers
+
+    @require_torch_multi_accelerator
+    def test_model_parallelism(self, tmp_path):
+        if self.model_class._no_split_modules is None:
+            pytest.skip("Test not supported for this model as `_no_split_modules` is not set.")
+
+        config = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**config).eval()
+
+        model = model.to(torch_device)
+
+        torch.manual_seed(0)
+        base_output = model(**inputs_dict, return_dict=False)[0]
+
+        model_size = compute_module_sizes(model)[""]
+        max_gpu_sizes = [int(p * model_size) for p in self.model_split_percents]
+
+        model.cpu().save_pretrained(tmp_path)
+
+        for max_size in max_gpu_sizes:
+            max_memory = {0: max_size, 1: model_size * 2, "cpu": model_size * 2}
+            new_model = self.model_class.from_pretrained(tmp_path, device_map="auto", max_memory=max_memory)
+            # Making sure part of the model will be on GPU 0 and GPU 1
+            assert set(new_model.hf_device_map.values()) == {0, 1}, "Model should be split across GPUs"
+
+            check_device_map_is_respected(new_model, new_model.hf_device_map)
+
+            torch.manual_seed(0)
+            new_output = new_model(**inputs_dict, return_dict=False)[0]
+
+            assert_tensors_close(
+                base_output, new_output, atol=1e-5, rtol=0, msg="Output should match with model parallelism"
+            )

tests/models/testing_utils/compile.py

@@ -0,0 +1,160 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import gc
+import os
+
+import pytest
+import torch
+
+from ...testing_utils import (
+    backend_empty_cache,
+    is_torch_compile,
+    require_accelerator,
+    require_torch_version_greater,
+    torch_device,
+)
+
+
+@is_torch_compile
+@require_accelerator
+@require_torch_version_greater("2.7.1")
+class TorchCompileTesterMixin:
+    """
+    Mixin class for testing torch.compile functionality on models.
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+        - different_shapes_for_compilation: Optional list of (height, width) tuples for dynamic shape testing
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: compile
+        Use `pytest -m "not compile"` to skip these tests
+    """
+
+    different_shapes_for_compilation = None
+
+    def setup_method(self):
+        torch.compiler.reset()
+        gc.collect()
+        backend_empty_cache(torch_device)
+
+    def teardown_method(self):
+        torch.compiler.reset()
+        gc.collect()
+        backend_empty_cache(torch_device)
+
+    def test_torch_compile_recompilation_and_graph_break(self):
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+        model = torch.compile(model, fullgraph=True)
+
+        with (
+            torch._inductor.utils.fresh_inductor_cache(),
+            torch._dynamo.config.patch(error_on_recompile=True),
+            torch.no_grad(),
+        ):
+            _ = model(**inputs_dict)
+            _ = model(**inputs_dict)
+
+    def test_torch_compile_repeated_blocks(self):
+        if self.model_class._repeated_blocks is None:
+            pytest.skip("Skipping test as the model class doesn't have `_repeated_blocks` set.")
+
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+        model.compile_repeated_blocks(fullgraph=True)
+
+        recompile_limit = 1
+        if self.model_class.__name__ == "UNet2DConditionModel":
+            recompile_limit = 2
+
+        with (
+            torch._inductor.utils.fresh_inductor_cache(),
+            torch._dynamo.config.patch(recompile_limit=recompile_limit),
+            torch.no_grad(),
+        ):
+            _ = model(**inputs_dict)
+            _ = model(**inputs_dict)
+
+    def test_compile_with_group_offloading(self):
+        if not self.model_class._supports_group_offloading:
+            pytest.skip("Model does not support group offloading.")
+
+        torch._dynamo.config.cache_size_limit = 10000
+
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict)
+        model.eval()
+
+        group_offload_kwargs = {
+            "onload_device": torch_device,
+            "offload_device": "cpu",
+            "offload_type": "block_level",
+            "num_blocks_per_group": 1,
+            "use_stream": True,
+            "non_blocking": True,
+        }
+        model.enable_group_offload(**group_offload_kwargs)
+        model.compile()
+
+        with torch.no_grad():
+            _ = model(**inputs_dict)
+            _ = model(**inputs_dict)
+
+    def test_compile_on_different_shapes(self):
+        if self.different_shapes_for_compilation is None:
+            pytest.skip(f"Skipping as `different_shapes_for_compilation` is not set for {self.__class__.__name__}.")
+        torch.fx.experimental._config.use_duck_shape = False
+
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.eval()
+        model = torch.compile(model, fullgraph=True, dynamic=True)
+
+        for height, width in self.different_shapes_for_compilation:
+            with torch._dynamo.config.patch(error_on_recompile=True), torch.no_grad():
+                inputs_dict = self.get_dummy_inputs(height=height, width=width)
+                _ = model(**inputs_dict)
+
+    def test_compile_works_with_aot(self, tmp_path):
+        from torch._inductor.package import load_package
+
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+
+        model = self.model_class(**init_dict).to(torch_device)
+        exported_model = torch.export.export(model, args=(), kwargs=inputs_dict)
+
+        package_path = os.path.join(str(tmp_path), f"{self.model_class.__name__}.pt2")
+        _ = torch._inductor.aoti_compile_and_package(exported_model, package_path=package_path)
+        assert os.path.exists(package_path), f"Package file not created at {package_path}"
+        loaded_binary = load_package(package_path, run_single_threaded=True)
+
+        model.forward = loaded_binary
+
+        with torch.no_grad():
+            _ = model(**inputs_dict)
+            _ = model(**inputs_dict)

tests/models/testing_utils/ip_adapter.py

@@ -0,0 +1,138 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import pytest
+import torch
+
+from ...testing_utils import is_ip_adapter, torch_device
+
+
+def check_if_ip_adapter_correctly_set(model, processor_cls) -> bool:
+    """
+    Check if IP Adapter processors are correctly set in the model.
+
+    Args:
+        model: The model to check
+
+    Returns:
+        bool: True if IP Adapter is correctly set, False otherwise
+    """
+    for module in model.attn_processors.values():
+        if isinstance(module, processor_cls):
+            return True
+    return False
+
+
+@is_ip_adapter
+class IPAdapterTesterMixin:
+    """
+    Mixin class for testing IP Adapter functionality on models.
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: ip_adapter
+        Use `pytest -m "not ip_adapter"` to skip these tests
+    """
+
+    ip_adapter_processor_cls = None
+
+    def create_ip_adapter_state_dict(self, model):
+        raise NotImplementedError("child class must implement method to create IPAdapter State Dict")
+
+    def modify_inputs_for_ip_adapter(self, model, inputs_dict):
+        raise NotImplementedError("child class must implement method to create IPAdapter model inputs")
+
+    def test_load_ip_adapter(self):
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        torch.manual_seed(0)
+        output_no_adapter = model(**inputs_dict, return_dict=False)[0]
+
+        ip_adapter_state_dict = self.create_ip_adapter_state_dict(model)
+
+        model._load_ip_adapter_weights([ip_adapter_state_dict])
+        assert check_if_ip_adapter_correctly_set(model, self.ip_adapter_processor_cls), (
+            "IP Adapter processors not set correctly"
+        )
+
+        inputs_dict_with_adapter = self.modify_inputs_for_ip_adapter(model, inputs_dict.copy())
+        outputs_with_adapter = model(**inputs_dict_with_adapter, return_dict=False)[0]
+
+        assert not torch.allclose(output_no_adapter, outputs_with_adapter, atol=1e-4, rtol=1e-4), (
+            "Output should differ with IP Adapter enabled"
+        )
+
+    @pytest.mark.skip(
+        reason="Setting IP Adapter scale is not defined at the model level. Enable this test after refactoring"
+    )
+    def test_ip_adapter_scale(self):
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        ip_adapter_state_dict = self.create_ip_adapter_state_dict(model)
+        model._load_ip_adapter_weights([ip_adapter_state_dict])
+
+        inputs_dict_with_adapter = self.modify_inputs_for_ip_adapter(model, inputs_dict.copy())
+
+        # Test scale = 0.0 (no effect)
+        model.set_ip_adapter_scale(0.0)
+        torch.manual_seed(0)
+        output_scale_zero = model(**inputs_dict_with_adapter, return_dict=False)[0]
+
+        # Test scale = 1.0 (full effect)
+        model.set_ip_adapter_scale(1.0)
+        torch.manual_seed(0)
+        output_scale_one = model(**inputs_dict_with_adapter, return_dict=False)[0]
+
+        # Outputs should differ with different scales
+        assert not torch.allclose(output_scale_zero, output_scale_one, atol=1e-4, rtol=1e-4), (
+            "Output should differ with different IP Adapter scales"
+        )
+
+    @pytest.mark.skip(
+        reason="Unloading IP Adapter is not defined at the model level. Enable this test after refactoring"
+    )
+    def test_unload_ip_adapter(self):
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        # Save original processors
+        original_processors = {k: type(v).__name__ for k, v in model.attn_processors.items()}
+
+        # Create and load IP adapter
+        ip_adapter_state_dict = self.create_ip_adapter_state_dict(model)
+        model._load_ip_adapter_weights([ip_adapter_state_dict])
+
+        assert check_if_ip_adapter_correctly_set(model, self.ip_adapter_processor_cls), "IP Adapter should be set"
+
+        # Unload IP adapter
+        model.unload_ip_adapter()
+
+        assert not check_if_ip_adapter_correctly_set(model, self.ip_adapter_processor_cls), (
+            "IP Adapter should be unloaded"
+        )
+
+        # Verify processors are restored
+        current_processors = {k: type(v).__name__ for k, v in model.attn_processors.items()}
+        assert original_processors == current_processors, "Processors should be restored after unload"

tests/models/testing_utils/lora.py

@@ -0,0 +1,548 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import gc
+import json
+import os
+import re
+
+import pytest
+import safetensors.torch
+import torch
+import torch.nn as nn
+
+from diffusers.utils.import_utils import is_peft_available
+from diffusers.utils.testing_utils import check_if_dicts_are_equal
+
+from ...testing_utils import (
+    assert_tensors_close,
+    backend_empty_cache,
+    is_lora,
+    is_torch_compile,
+    require_peft_backend,
+    require_peft_version_greater,
+    require_torch_accelerator,
+    require_torch_version_greater,
+    torch_device,
+)
+
+
+if is_peft_available():
+    from diffusers.loaders.peft import PeftAdapterMixin
+
+
+def check_if_lora_correctly_set(model) -> bool:
+    """
+    Check if LoRA layers are correctly set in the model.
+
+    Args:
+        model: The model to check
+
+    Returns:
+        bool: True if LoRA is correctly set, False otherwise
+    """
+    from peft.tuners.tuners_utils import BaseTunerLayer
+
+    for module in model.modules():
+        if isinstance(module, BaseTunerLayer):
+            return True
+    return False
+
+
+@is_lora
+@require_peft_backend
+class LoraTesterMixin:
+    """
+    Mixin class for testing LoRA/PEFT functionality on models.
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: lora
+        Use `pytest -m "not lora"` to skip these tests
+    """
+
+    def setup_method(self):
+        if not issubclass(self.model_class, PeftAdapterMixin):
+            pytest.skip(f"PEFT is not supported for this model ({self.model_class.__name__}).")
+
+    def test_save_load_lora_adapter(self, tmp_path, rank=4, lora_alpha=4, use_dora=False):
+        from peft import LoraConfig
+        from peft.utils import get_peft_model_state_dict
+
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        torch.manual_seed(0)
+        output_no_lora = model(**inputs_dict, return_dict=False)[0]
+
+        denoiser_lora_config = LoraConfig(
+            r=rank,
+            lora_alpha=lora_alpha,
+            target_modules=["to_q", "to_k", "to_v", "to_out.0"],
+            init_lora_weights=False,
+            use_dora=use_dora,
+        )
+        model.add_adapter(denoiser_lora_config)
+        assert check_if_lora_correctly_set(model), "LoRA layers not set correctly"
+
+        torch.manual_seed(0)
+        outputs_with_lora = model(**inputs_dict, return_dict=False)[0]
+
+        assert not torch.allclose(output_no_lora, outputs_with_lora, atol=1e-4, rtol=1e-4), (
+            "Output should differ with LoRA enabled"
+        )
+
+        model.save_lora_adapter(tmp_path)
+        assert os.path.isfile(os.path.join(tmp_path, "pytorch_lora_weights.safetensors")), (
+            "LoRA weights file not created"
+        )
+
+        state_dict_loaded = safetensors.torch.load_file(os.path.join(tmp_path, "pytorch_lora_weights.safetensors"))
+
+        model.unload_lora()
+        assert not check_if_lora_correctly_set(model), "LoRA should be unloaded"
+
+        model.load_lora_adapter(tmp_path, prefix=None, use_safetensors=True)
+        state_dict_retrieved = get_peft_model_state_dict(model, adapter_name="default_0")
+
+        for k in state_dict_loaded:
+            loaded_v = state_dict_loaded[k]
+            retrieved_v = state_dict_retrieved[k].to(loaded_v.device)
+            assert_tensors_close(loaded_v, retrieved_v, atol=1e-5, rtol=0, msg=f"Mismatch in LoRA weight {k}")
+
+        assert check_if_lora_correctly_set(model), "LoRA layers not set correctly after reload"
+
+        torch.manual_seed(0)
+        outputs_with_lora_2 = model(**inputs_dict, return_dict=False)[0]
+
+        assert not torch.allclose(output_no_lora, outputs_with_lora_2, atol=1e-4, rtol=1e-4), (
+            "Output should differ with LoRA enabled"
+        )
+        assert_tensors_close(
+            outputs_with_lora,
+            outputs_with_lora_2,
+            atol=1e-4,
+            rtol=1e-4,
+            msg="Outputs should match before and after save/load",
+        )
+
+    def test_lora_wrong_adapter_name_raises_error(self, tmp_path):
+        from peft import LoraConfig
+
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        denoiser_lora_config = LoraConfig(
+            r=4,
+            lora_alpha=4,
+            target_modules=["to_q", "to_k", "to_v", "to_out.0"],
+            init_lora_weights=False,
+            use_dora=False,
+        )
+        model.add_adapter(denoiser_lora_config)
+        assert check_if_lora_correctly_set(model), "LoRA layers not set correctly"
+
+        wrong_name = "foo"
+        with pytest.raises(ValueError) as exc_info:
+            model.save_lora_adapter(tmp_path, adapter_name=wrong_name)
+
+        assert f"Adapter name {wrong_name} not found in the model." in str(exc_info.value)
+
+    def test_lora_adapter_metadata_is_loaded_correctly(self, tmp_path, rank=4, lora_alpha=4, use_dora=False):
+        from peft import LoraConfig
+
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        denoiser_lora_config = LoraConfig(
+            r=rank,
+            lora_alpha=lora_alpha,
+            target_modules=["to_q", "to_k", "to_v", "to_out.0"],
+            init_lora_weights=False,
+            use_dora=use_dora,
+        )
+        model.add_adapter(denoiser_lora_config)
+        metadata = model.peft_config["default"].to_dict()
+        assert check_if_lora_correctly_set(model), "LoRA layers not set correctly"
+
+        model.save_lora_adapter(tmp_path)
+        model_file = os.path.join(tmp_path, "pytorch_lora_weights.safetensors")
+        assert os.path.isfile(model_file), "LoRA weights file not created"
+
+        model.unload_lora()
+        assert not check_if_lora_correctly_set(model), "LoRA should be unloaded"
+
+        model.load_lora_adapter(tmp_path, prefix=None, use_safetensors=True)
+        parsed_metadata = model.peft_config["default_0"].to_dict()
+        check_if_dicts_are_equal(metadata, parsed_metadata)
+
+    def test_lora_adapter_wrong_metadata_raises_error(self, tmp_path):
+        from peft import LoraConfig
+
+        from diffusers.loaders.lora_base import LORA_ADAPTER_METADATA_KEY
+
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        denoiser_lora_config = LoraConfig(
+            r=4,
+            lora_alpha=4,
+            target_modules=["to_q", "to_k", "to_v", "to_out.0"],
+            init_lora_weights=False,
+            use_dora=False,
+        )
+        model.add_adapter(denoiser_lora_config)
+        assert check_if_lora_correctly_set(model), "LoRA layers not set correctly"
+
+        model.save_lora_adapter(tmp_path)
+        model_file = os.path.join(tmp_path, "pytorch_lora_weights.safetensors")
+        assert os.path.isfile(model_file), "LoRA weights file not created"
+
+        # Perturb the metadata in the state dict
+        loaded_state_dict = safetensors.torch.load_file(model_file)
+        metadata = {"format": "pt"}
+        lora_adapter_metadata = denoiser_lora_config.to_dict()
+        lora_adapter_metadata.update({"foo": 1, "bar": 2})
+        for key, value in lora_adapter_metadata.items():
+            if isinstance(value, set):
+                lora_adapter_metadata[key] = list(value)
+        metadata[LORA_ADAPTER_METADATA_KEY] = json.dumps(lora_adapter_metadata, indent=2, sort_keys=True)
+        safetensors.torch.save_file(loaded_state_dict, model_file, metadata=metadata)
+
+        model.unload_lora()
+        assert not check_if_lora_correctly_set(model), "LoRA should be unloaded"
+
+        with pytest.raises(TypeError) as exc_info:
+            model.load_lora_adapter(tmp_path, prefix=None, use_safetensors=True)
+        assert "`LoraConfig` class could not be instantiated" in str(exc_info.value)
+
+
+@is_lora
+@is_torch_compile
+@require_peft_backend
+@require_peft_version_greater("0.14.0")
+@require_torch_version_greater("2.7.1")
+@require_torch_accelerator
+class LoraHotSwappingForModelTesterMixin:
+    """
+    Mixin class for testing LoRA hot swapping functionality on models.
+
+    Test that hotswapping does not result in recompilation on the model directly.
+    We're not extensively testing the hotswapping functionality since it is implemented in PEFT
+    and is extensively tested there. The goal of this test is specifically to ensure that
+    hotswapping with diffusers does not require recompilation.
+
+    See https://github.com/huggingface/peft/blob/eaab05e18d51fb4cce20a73c9acd82a00c013b83/tests/test_gpu_examples.py#L4252
+    for the analogous PEFT test.
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+        - different_shapes_for_compilation: Optional list of (height, width) tuples for dynamic compilation tests
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest marks: lora, torch_compile
+        Use `pytest -m "not lora"` or `pytest -m "not torch_compile"` to skip these tests
+    """
+
+    different_shapes_for_compilation = None
+
+    def setup_method(self):
+        if not issubclass(self.model_class, PeftAdapterMixin):
+            pytest.skip(f"PEFT is not supported for this model ({self.model_class.__name__}).")
+
+    def teardown_method(self):
+        # It is critical that the dynamo cache is reset for each test. Otherwise, if the test re-uses the same model,
+        # there will be recompilation errors, as torch caches the model when run in the same process.
+        torch.compiler.reset()
+        gc.collect()
+        backend_empty_cache(torch_device)
+
+    def _get_lora_config(self, lora_rank, lora_alpha, target_modules):
+        from peft import LoraConfig
+
+        lora_config = LoraConfig(
+            r=lora_rank,
+            lora_alpha=lora_alpha,
+            target_modules=target_modules,
+            init_lora_weights=False,
+            use_dora=False,
+        )
+        return lora_config
+
+    def _get_linear_module_name_other_than_attn(self, model):
+        linear_names = [
+            name for name, module in model.named_modules() if isinstance(module, nn.Linear) and "to_" not in name
+        ]
+        return linear_names[0]
+
+    def _check_model_hotswap(self, tmp_path, do_compile, rank0, rank1, target_modules0, target_modules1=None):
+        """
+        Check that hotswapping works on a model.
+
+        Steps:
+        - create 2 LoRA adapters and save them
+        - load the first adapter
+        - hotswap the second adapter
+        - check that the outputs are correct
+        - optionally compile the model
+        - optionally check if recompilations happen on different shapes
+
+        Note: We set rank == alpha here because save_lora_adapter does not save the alpha scalings, thus the test would
+        fail if the values are different. Since rank != alpha does not matter for the purpose of this test, this is
+        fine.
+        """
+        different_shapes = self.different_shapes_for_compilation
+        # create 2 adapters with different ranks and alphas
+        torch.manual_seed(0)
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        alpha0, alpha1 = rank0, rank1
+        max_rank = max([rank0, rank1])
+        if target_modules1 is None:
+            target_modules1 = target_modules0[:]
+        lora_config0 = self._get_lora_config(rank0, alpha0, target_modules0)
+        lora_config1 = self._get_lora_config(rank1, alpha1, target_modules1)
+
+        model.add_adapter(lora_config0, adapter_name="adapter0")
+        with torch.inference_mode():
+            torch.manual_seed(0)
+            output0_before = model(**inputs_dict)["sample"]
+
+        model.add_adapter(lora_config1, adapter_name="adapter1")
+        model.set_adapter("adapter1")
+        with torch.inference_mode():
+            torch.manual_seed(0)
+            output1_before = model(**inputs_dict)["sample"]
+
+        # sanity checks:
+        tol = 5e-3
+        assert not torch.allclose(output0_before, output1_before, atol=tol, rtol=tol)
+        assert not (output0_before == 0).all()
+        assert not (output1_before == 0).all()
+
+        # save the adapter checkpoints
+        model.save_lora_adapter(os.path.join(tmp_path, "0"), safe_serialization=True, adapter_name="adapter0")
+        model.save_lora_adapter(os.path.join(tmp_path, "1"), safe_serialization=True, adapter_name="adapter1")
+        del model
+
+        # load the first adapter
+        torch.manual_seed(0)
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+
+        if do_compile or (rank0 != rank1):
+            # no need to prepare if the model is not compiled or if the ranks are identical
+            model.enable_lora_hotswap(target_rank=max_rank)
+
+        file_name0 = os.path.join(os.path.join(tmp_path, "0"), "pytorch_lora_weights.safetensors")
+        file_name1 = os.path.join(os.path.join(tmp_path, "1"), "pytorch_lora_weights.safetensors")
+        model.load_lora_adapter(file_name0, safe_serialization=True, adapter_name="adapter0", prefix=None)
+
+        if do_compile:
+            model = torch.compile(model, mode="reduce-overhead", dynamic=different_shapes is not None)
+
+        with torch.inference_mode():
+            # additionally check if dynamic compilation works.
+            if different_shapes is not None:
+                for height, width in different_shapes:
+                    new_inputs_dict = self.prepare_dummy_input(height=height, width=width)
+                    _ = model(**new_inputs_dict)
+            else:
+                output0_after = model(**inputs_dict)["sample"]
+                assert_tensors_close(
+                    output0_before, output0_after, atol=tol, rtol=tol, msg="Output mismatch after loading adapter0"
+                )
+
+        # hotswap the 2nd adapter
+        model.load_lora_adapter(file_name1, adapter_name="adapter0", hotswap=True, prefix=None)
+
+        # we need to call forward to potentially trigger recompilation
+        with torch.inference_mode():
+            if different_shapes is not None:
+                for height, width in different_shapes:
+                    new_inputs_dict = self.prepare_dummy_input(height=height, width=width)
+                    _ = model(**new_inputs_dict)
+            else:
+                output1_after = model(**inputs_dict)["sample"]
+                assert_tensors_close(
+                    output1_before,
+                    output1_after,
+                    atol=tol,
+                    rtol=tol,
+                    msg="Output mismatch after hotswapping to adapter1",
+                )
+
+        # check error when not passing valid adapter name
+        name = "does-not-exist"
+        msg = f"Trying to hotswap LoRA adapter '{name}' but there is no existing adapter by that name"
+        with pytest.raises(ValueError, match=re.escape(msg)):
+            model.load_lora_adapter(file_name1, adapter_name=name, hotswap=True, prefix=None)
+
+    @pytest.mark.parametrize("rank0,rank1", [(11, 11), (7, 13), (13, 7)])
+    def test_hotswapping_model(self, tmp_path, rank0, rank1):
+        self._check_model_hotswap(
+            tmp_path, do_compile=False, rank0=rank0, rank1=rank1, target_modules0=["to_q", "to_k", "to_v", "to_out.0"]
+        )
+
+    @pytest.mark.parametrize("rank0,rank1", [(11, 11), (7, 13), (13, 7)])
+    def test_hotswapping_compiled_model_linear(self, tmp_path, rank0, rank1):
+        # It's important to add this context to raise an error on recompilation
+        target_modules = ["to_q", "to_k", "to_v", "to_out.0"]
+        with torch._dynamo.config.patch(error_on_recompile=True), torch._inductor.utils.fresh_inductor_cache():
+            self._check_model_hotswap(
+                tmp_path, do_compile=True, rank0=rank0, rank1=rank1, target_modules0=target_modules
+            )
+
+    @pytest.mark.parametrize("rank0,rank1", [(11, 11), (7, 13), (13, 7)])
+    def test_hotswapping_compiled_model_conv2d(self, tmp_path, rank0, rank1):
+        if "unet" not in self.model_class.__name__.lower():
+            pytest.skip("Test only applies to UNet.")
+
+        # It's important to add this context to raise an error on recompilation
+        target_modules = ["conv", "conv1", "conv2"]
+        with torch._dynamo.config.patch(error_on_recompile=True), torch._inductor.utils.fresh_inductor_cache():
+            self._check_model_hotswap(
+                tmp_path, do_compile=True, rank0=rank0, rank1=rank1, target_modules0=target_modules
+            )
+
+    @pytest.mark.parametrize("rank0,rank1", [(11, 11), (7, 13), (13, 7)])
+    def test_hotswapping_compiled_model_both_linear_and_conv2d(self, tmp_path, rank0, rank1):
+        if "unet" not in self.model_class.__name__.lower():
+            pytest.skip("Test only applies to UNet.")
+
+        # It's important to add this context to raise an error on recompilation
+        target_modules = ["to_q", "conv"]
+        with torch._dynamo.config.patch(error_on_recompile=True), torch._inductor.utils.fresh_inductor_cache():
+            self._check_model_hotswap(
+                tmp_path, do_compile=True, rank0=rank0, rank1=rank1, target_modules0=target_modules
+            )
+
+    @pytest.mark.parametrize("rank0,rank1", [(11, 11), (7, 13), (13, 7)])
+    def test_hotswapping_compiled_model_both_linear_and_other(self, tmp_path, rank0, rank1):
+        # In `test_hotswapping_compiled_model_both_linear_and_conv2d()`, we check if we can do hotswapping
+        # with `torch.compile()` for models that have both linear and conv layers. In this test, we check
+        # if we can target a linear layer from the transformer blocks and another linear layer from non-attention
+        # block.
+        target_modules = ["to_q"]
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict)
+
+        target_modules.append(self._get_linear_module_name_other_than_attn(model))
+        del model
+
+        # It's important to add this context to raise an error on recompilation
+        with torch._dynamo.config.patch(error_on_recompile=True):
+            self._check_model_hotswap(
+                tmp_path, do_compile=True, rank0=rank0, rank1=rank1, target_modules0=target_modules
+            )
+
+    def test_enable_lora_hotswap_called_after_adapter_added_raises(self):
+        # ensure that enable_lora_hotswap is called before loading the first adapter
+        lora_config = self._get_lora_config(8, 8, target_modules=["to_q"])
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.add_adapter(lora_config)
+
+        msg = re.escape("Call `enable_lora_hotswap` before loading the first adapter.")
+        with pytest.raises(RuntimeError, match=msg):
+            model.enable_lora_hotswap(target_rank=32)
+
+    def test_enable_lora_hotswap_called_after_adapter_added_warning(self, caplog):
+        # ensure that enable_lora_hotswap is called before loading the first adapter
+        import logging
+
+        lora_config = self._get_lora_config(8, 8, target_modules=["to_q"])
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.add_adapter(lora_config)
+        msg = (
+            "It is recommended to call `enable_lora_hotswap` before loading the first adapter to avoid recompilation."
+        )
+        with caplog.at_level(logging.WARNING):
+            model.enable_lora_hotswap(target_rank=32, check_compiled="warn")
+            assert any(msg in record.message for record in caplog.records)
+
+    def test_enable_lora_hotswap_called_after_adapter_added_ignore(self, caplog):
+        # check possibility to ignore the error/warning
+        import logging
+
+        lora_config = self._get_lora_config(8, 8, target_modules=["to_q"])
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.add_adapter(lora_config)
+        with caplog.at_level(logging.WARNING):
+            model.enable_lora_hotswap(target_rank=32, check_compiled="ignore")
+            assert len(caplog.records) == 0
+
+    def test_enable_lora_hotswap_wrong_check_compiled_argument_raises(self):
+        # check that wrong argument value raises an error
+        lora_config = self._get_lora_config(8, 8, target_modules=["to_q"])
+        init_dict = self.get_init_dict()
+        model = self.model_class(**init_dict).to(torch_device)
+        model.add_adapter(lora_config)
+        msg = re.escape("check_compiles should be one of 'error', 'warn', or 'ignore', got 'wrong-argument' instead.")
+        with pytest.raises(ValueError, match=msg):
+            model.enable_lora_hotswap(target_rank=32, check_compiled="wrong-argument")
+
+    def test_hotswap_second_adapter_targets_more_layers_raises(self, tmp_path, caplog):
+        # check the error and log
+        import logging
+
+        # at the moment, PEFT requires the 2nd adapter to target the same or a subset of layers
+        target_modules0 = ["to_q"]
+        target_modules1 = ["to_q", "to_k"]
+        with pytest.raises(RuntimeError):  # peft raises RuntimeError
+            with caplog.at_level(logging.ERROR):
+                self._check_model_hotswap(
+                    tmp_path,
+                    do_compile=True,
+                    rank0=8,
+                    rank1=8,
+                    target_modules0=target_modules0,
+                    target_modules1=target_modules1,
+                )
+                assert any("Hotswapping adapter0 was unsuccessful" in record.message for record in caplog.records)
+
+    @pytest.mark.parametrize("rank0,rank1", [(11, 11), (7, 13), (13, 7)])
+    @require_torch_version_greater("2.7.1")
+    def test_hotswapping_compile_on_different_shapes(self, tmp_path, rank0, rank1):
+        different_shapes_for_compilation = self.different_shapes_for_compilation
+        if different_shapes_for_compilation is None:
+            pytest.skip(f"Skipping as `different_shapes_for_compilation` is not set for {self.__class__.__name__}.")
+        # Specifying `use_duck_shape=False` instructs the compiler if it should use the same symbolic
+        # variable to represent input sizes that are the same. For more details,
+        # check out this [comment](https://github.com/huggingface/diffusers/pull/11327#discussion_r2047659790).
+        torch.fx.experimental._config.use_duck_shape = False
+
+        target_modules = ["to_q", "to_k", "to_v", "to_out.0"]
+        with torch._dynamo.config.patch(error_on_recompile=True):
+            self._check_model_hotswap(
+                tmp_path,
+                do_compile=True,
+                rank0=rank0,
+                rank1=rank1,
+                target_modules0=target_modules,
+            )

tests/models/testing_utils/memory.py

@@ -0,0 +1,493 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import gc
+import glob
+import inspect
+from functools import wraps
+
+import pytest
+import torch
+from accelerate.utils.modeling import compute_module_sizes
+
+from diffusers.utils.testing_utils import _check_safetensors_serialization
+from diffusers.utils.torch_utils import get_torch_cuda_device_capability
+
+from ...testing_utils import (
+    assert_tensors_close,
+    backend_empty_cache,
+    backend_max_memory_allocated,
+    backend_reset_peak_memory_stats,
+    backend_synchronize,
+    is_cpu_offload,
+    is_group_offload,
+    is_memory,
+    require_accelerator,
+    torch_device,
+)
+from .common import check_device_map_is_respected
+
+
+def cast_maybe_tensor_dtype(inputs_dict, from_dtype, to_dtype):
+    """Helper to cast tensor inputs from one dtype to another."""
+    for key, value in inputs_dict.items():
+        if isinstance(value, torch.Tensor) and value.dtype == from_dtype:
+            inputs_dict[key] = value.to(to_dtype)
+    return inputs_dict
+
+
+def require_offload_support(func):
+    """
+    Decorator to skip tests if model doesn't support offloading (requires _no_split_modules).
+    """
+
+    @wraps(func)
+    def wrapper(self, *args, **kwargs):
+        if self.model_class._no_split_modules is None:
+            pytest.skip("Test not supported for this model as `_no_split_modules` is not set.")
+        return func(self, *args, **kwargs)
+
+    return wrapper
+
+
+def require_group_offload_support(func):
+    """
+    Decorator to skip tests if model doesn't support group offloading.
+    """
+
+    @wraps(func)
+    def wrapper(self, *args, **kwargs):
+        if not self.model_class._supports_group_offloading:
+            pytest.skip("Model does not support group offloading.")
+        return func(self, *args, **kwargs)
+
+    return wrapper
+
+
+@is_cpu_offload
+class CPUOffloadTesterMixin:
+    """
+    Mixin class for testing CPU offloading functionality.
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+        - model_split_percents: List of percentages for splitting model across devices
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: cpu_offload
+        Use `pytest -m "not cpu_offload"` to skip these tests
+    """
+
+    model_split_percents = [0.5, 0.7]
+
+    @require_offload_support
+    def test_cpu_offload(self, tmp_path):
+        config = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**config).eval()
+
+        model = model.to(torch_device)
+
+        torch.manual_seed(0)
+        base_output = model(**inputs_dict)
+
+        model_size = compute_module_sizes(model)[""]
+        # We test several splits of sizes to make sure it works
+        max_gpu_sizes = [int(p * model_size) for p in self.model_split_percents]
+        model.cpu().save_pretrained(str(tmp_path))
+
+        for max_size in max_gpu_sizes:
+            max_memory = {0: max_size, "cpu": model_size * 2}
+            new_model = self.model_class.from_pretrained(str(tmp_path), device_map="auto", max_memory=max_memory)
+            # Making sure part of the model will actually end up offloaded
+            assert set(new_model.hf_device_map.values()) == {0, "cpu"}, "Model should be split between GPU and CPU"
+
+            check_device_map_is_respected(new_model, new_model.hf_device_map)
+            torch.manual_seed(0)
+            new_output = new_model(**inputs_dict)
+
+            assert_tensors_close(
+                base_output[0], new_output[0], atol=1e-5, rtol=0, msg="Output should match with CPU offloading"
+            )
+
+    @require_offload_support
+    def test_disk_offload_without_safetensors(self, tmp_path):
+        config = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**config).eval()
+
+        model = model.to(torch_device)
+
+        torch.manual_seed(0)
+        base_output = model(**inputs_dict)
+
+        model_size = compute_module_sizes(model)[""]
+        max_size = int(self.model_split_percents[0] * model_size)
+        # Force disk offload by setting very small CPU memory
+        max_memory = {0: max_size, "cpu": int(0.1 * max_size)}
+
+        model.cpu().save_pretrained(str(tmp_path), safe_serialization=False)
+        # This errors out because it's missing an offload folder
+        with pytest.raises(ValueError):
+            new_model = self.model_class.from_pretrained(str(tmp_path), device_map="auto", max_memory=max_memory)
+
+        new_model = self.model_class.from_pretrained(
+            str(tmp_path), device_map="auto", max_memory=max_memory, offload_folder=str(tmp_path)
+        )
+
+        check_device_map_is_respected(new_model, new_model.hf_device_map)
+        torch.manual_seed(0)
+        new_output = new_model(**inputs_dict)
+
+        assert_tensors_close(
+            base_output[0], new_output[0], atol=1e-5, rtol=0, msg="Output should match with disk offloading"
+        )
+
+    @require_offload_support
+    def test_disk_offload_with_safetensors(self, tmp_path):
+        config = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**config).eval()
+
+        model = model.to(torch_device)
+
+        torch.manual_seed(0)
+        base_output = model(**inputs_dict)
+
+        model_size = compute_module_sizes(model)[""]
+        model.cpu().save_pretrained(str(tmp_path))
+
+        max_size = int(self.model_split_percents[0] * model_size)
+        max_memory = {0: max_size, "cpu": max_size}
+        new_model = self.model_class.from_pretrained(
+            str(tmp_path), device_map="auto", offload_folder=str(tmp_path), max_memory=max_memory
+        )
+
+        check_device_map_is_respected(new_model, new_model.hf_device_map)
+        torch.manual_seed(0)
+        new_output = new_model(**inputs_dict)
+
+        assert_tensors_close(
+            base_output[0],
+            new_output[0],
+            atol=1e-5,
+            rtol=0,
+            msg="Output should match with disk offloading (safetensors)",
+        )
+
+
+@is_group_offload
+class GroupOffloadTesterMixin:
+    """
+    Mixin class for testing group offloading functionality.
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: group_offload
+        Use `pytest -m "not group_offload"` to skip these tests
+    """
+
+    @require_group_offload_support
+    def test_group_offloading(self, record_stream=False):
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        torch.manual_seed(0)
+
+        @torch.no_grad()
+        def run_forward(model):
+            assert all(
+                module._diffusers_hook.get_hook("group_offloading") is not None
+                for module in model.modules()
+                if hasattr(module, "_diffusers_hook")
+            ), "Group offloading hook should be set"
+            model.eval()
+            return model(**inputs_dict)[0]
+
+        model = self.model_class(**init_dict)
+
+        model.to(torch_device)
+        output_without_group_offloading = run_forward(model)
+
+        torch.manual_seed(0)
+        model = self.model_class(**init_dict)
+        model.enable_group_offload(torch_device, offload_type="block_level", num_blocks_per_group=1)
+        output_with_group_offloading1 = run_forward(model)
+
+        torch.manual_seed(0)
+        model = self.model_class(**init_dict)
+        model.enable_group_offload(torch_device, offload_type="block_level", num_blocks_per_group=1, non_blocking=True)
+        output_with_group_offloading2 = run_forward(model)
+
+        torch.manual_seed(0)
+        model = self.model_class(**init_dict)
+        model.enable_group_offload(torch_device, offload_type="leaf_level")
+        output_with_group_offloading3 = run_forward(model)
+
+        torch.manual_seed(0)
+        model = self.model_class(**init_dict)
+        model.enable_group_offload(
+            torch_device, offload_type="leaf_level", use_stream=True, record_stream=record_stream
+        )
+        output_with_group_offloading4 = run_forward(model)
+
+        assert_tensors_close(
+            output_without_group_offloading,
+            output_with_group_offloading1,
+            atol=1e-5,
+            rtol=0,
+            msg="Output should match with block-level offloading",
+        )
+        assert_tensors_close(
+            output_without_group_offloading,
+            output_with_group_offloading2,
+            atol=1e-5,
+            rtol=0,
+            msg="Output should match with non-blocking block-level offloading",
+        )
+        assert_tensors_close(
+            output_without_group_offloading,
+            output_with_group_offloading3,
+            atol=1e-5,
+            rtol=0,
+            msg="Output should match with leaf-level offloading",
+        )
+        assert_tensors_close(
+            output_without_group_offloading,
+            output_with_group_offloading4,
+            atol=1e-5,
+            rtol=0,
+            msg="Output should match with leaf-level offloading with stream",
+        )
+
+    @require_group_offload_support
+    @torch.no_grad()
+    def test_group_offloading_with_layerwise_casting(self, record_stream=False, offload_type="block_level"):
+        torch.manual_seed(0)
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        model = self.model_class(**init_dict)
+
+        model.to(torch_device)
+        model.eval()
+        _ = model(**inputs_dict)[0]
+
+        torch.manual_seed(0)
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        storage_dtype, compute_dtype = torch.float16, torch.float32
+        inputs_dict = cast_maybe_tensor_dtype(inputs_dict, torch.float32, compute_dtype)
+        model = self.model_class(**init_dict)
+        model.eval()
+        additional_kwargs = {} if offload_type == "leaf_level" else {"num_blocks_per_group": 1}
+        model.enable_group_offload(
+            torch_device, offload_type=offload_type, use_stream=True, record_stream=record_stream, **additional_kwargs
+        )
+        model.enable_layerwise_casting(storage_dtype=storage_dtype, compute_dtype=compute_dtype)
+        _ = model(**inputs_dict)[0]
+
+    @require_group_offload_support
+    @torch.no_grad()
+    @torch.inference_mode()
+    def test_group_offloading_with_disk(self, tmp_path, offload_type="block_level", record_stream=False, atol=1e-5):
+        def _has_generator_arg(model):
+            sig = inspect.signature(model.forward)
+            params = sig.parameters
+            return "generator" in params
+
+        def _run_forward(model, inputs_dict):
+            accepts_generator = _has_generator_arg(model)
+            if accepts_generator:
+                inputs_dict["generator"] = torch.manual_seed(0)
+            torch.manual_seed(0)
+            return model(**inputs_dict)[0]
+
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        torch.manual_seed(0)
+        model = self.model_class(**init_dict)
+
+        model.eval()
+        model.to(torch_device)
+        output_without_group_offloading = _run_forward(model, inputs_dict)
+
+        torch.manual_seed(0)
+        model = self.model_class(**init_dict)
+        model.eval()
+
+        num_blocks_per_group = None if offload_type == "leaf_level" else 1
+        additional_kwargs = {} if offload_type == "leaf_level" else {"num_blocks_per_group": num_blocks_per_group}
+        tmpdir = str(tmp_path)
+        model.enable_group_offload(
+            torch_device,
+            offload_type=offload_type,
+            offload_to_disk_path=tmpdir,
+            use_stream=True,
+            record_stream=record_stream,
+            **additional_kwargs,
+        )
+        has_safetensors = glob.glob(f"{tmpdir}/*.safetensors")
+        assert has_safetensors, "No safetensors found in the directory."
+
+        # For "leaf-level", there is a prefetching hook which makes this check a bit non-deterministic
+        # in nature. So, skip it.
+        if offload_type != "leaf_level":
+            is_correct, extra_files, missing_files = _check_safetensors_serialization(
+                module=model,
+                offload_to_disk_path=tmpdir,
+                offload_type=offload_type,
+                num_blocks_per_group=num_blocks_per_group,
+            )
+            if not is_correct:
+                if extra_files:
+                    raise ValueError(f"Found extra files: {', '.join(extra_files)}")
+                elif missing_files:
+                    raise ValueError(f"Following files are missing: {', '.join(missing_files)}")
+
+        output_with_group_offloading = _run_forward(model, inputs_dict)
+        assert_tensors_close(
+            output_without_group_offloading,
+            output_with_group_offloading,
+            atol=atol,
+            rtol=0,
+            msg="Output should match with disk-based group offloading",
+        )
+
+
+class LayerwiseCastingTesterMixin:
+    """
+    Mixin class for testing layerwise dtype casting for memory optimization.
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+    """
+
+    @torch.no_grad()
+    def test_layerwise_casting_memory(self):
+        MB_TOLERANCE = 0.2
+        LEAST_COMPUTE_CAPABILITY = 8.0
+
+        def reset_memory_stats():
+            gc.collect()
+            backend_synchronize(torch_device)
+            backend_empty_cache(torch_device)
+            backend_reset_peak_memory_stats(torch_device)
+
+        def get_memory_usage(storage_dtype, compute_dtype):
+            torch.manual_seed(0)
+            config = self.get_init_dict()
+            inputs_dict = self.get_dummy_inputs()
+            inputs_dict = cast_maybe_tensor_dtype(inputs_dict, torch.float32, compute_dtype)
+            model = self.model_class(**config).eval()
+            model = model.to(torch_device, dtype=compute_dtype)
+            model.enable_layerwise_casting(storage_dtype=storage_dtype, compute_dtype=compute_dtype)
+
+            reset_memory_stats()
+            model(**inputs_dict)
+            model_memory_footprint = model.get_memory_footprint()
+            peak_inference_memory_allocated_mb = backend_max_memory_allocated(torch_device) / 1024**2
+
+            return model_memory_footprint, peak_inference_memory_allocated_mb
+
+        fp32_memory_footprint, fp32_max_memory = get_memory_usage(torch.float32, torch.float32)
+        fp8_e4m3_fp32_memory_footprint, fp8_e4m3_fp32_max_memory = get_memory_usage(torch.float8_e4m3fn, torch.float32)
+        fp8_e4m3_bf16_memory_footprint, fp8_e4m3_bf16_max_memory = get_memory_usage(
+            torch.float8_e4m3fn, torch.bfloat16
+        )
+
+        compute_capability = get_torch_cuda_device_capability() if torch_device == "cuda" else None
+        assert fp8_e4m3_bf16_memory_footprint < fp8_e4m3_fp32_memory_footprint < fp32_memory_footprint, (
+            "Memory footprint should decrease with lower precision storage"
+        )
+
+        # NOTE: the following assertion would fail on our CI (running Tesla T4) due to bf16 using more memory than fp32.
+        # On other devices, such as DGX (Ampere) and Audace (Ada), the test passes. So, we conditionally check it.
+        if compute_capability and compute_capability >= LEAST_COMPUTE_CAPABILITY:
+            assert fp8_e4m3_bf16_max_memory < fp8_e4m3_fp32_max_memory, (
+                "Peak memory should be lower with bf16 compute on newer GPUs"
+            )
+
+        # On this dummy test case with a small model, sometimes fp8_e4m3_fp32 max memory usage is higher than fp32 by a few
+        # bytes. This only happens for some models, so we allow a small tolerance.
+        # For any real model being tested, the order would be fp8_e4m3_bf16 < fp8_e4m3_fp32 < fp32.
+        assert (
+            fp8_e4m3_fp32_max_memory < fp32_max_memory
+            or abs(fp8_e4m3_fp32_max_memory - fp32_max_memory) < MB_TOLERANCE
+        ), "Peak memory should be lower or within tolerance with fp8 storage"
+
+    def test_layerwise_casting_training(self):
+        def test_fn(storage_dtype, compute_dtype):
+            if torch.device(torch_device).type == "cpu" and compute_dtype == torch.bfloat16:
+                pytest.skip("Skipping test because CPU doesn't go well with bfloat16.")
+
+            model = self.model_class(**self.get_init_dict())
+            model = model.to(torch_device, dtype=compute_dtype)
+            model.enable_layerwise_casting(storage_dtype=storage_dtype, compute_dtype=compute_dtype)
+            model.train()
+
+            inputs_dict = self.get_inputs_dict()
+            inputs_dict = cast_maybe_tensor_dtype(inputs_dict, torch.float32, compute_dtype)
+            with torch.amp.autocast(device_type=torch.device(torch_device).type):
+                output = model(**inputs_dict, return_dict=False)[0]
+
+                input_tensor = inputs_dict[self.main_input_name]
+                noise = torch.randn((input_tensor.shape[0],) + self.output_shape).to(torch_device)
+                noise = cast_maybe_tensor_dtype(noise, torch.float32, compute_dtype)
+                loss = torch.nn.functional.mse_loss(output, noise)
+
+            loss.backward()
+
+        test_fn(torch.float16, torch.float32)
+        test_fn(torch.float8_e4m3fn, torch.float32)
+        test_fn(torch.float8_e5m2, torch.float32)
+        test_fn(torch.float8_e4m3fn, torch.bfloat16)
+
+
+@is_memory
+@require_accelerator
+class MemoryTesterMixin(CPUOffloadTesterMixin, GroupOffloadTesterMixin, LayerwiseCastingTesterMixin):
+    """
+    Combined mixin class for all memory optimization tests including CPU/disk offloading,
+    group offloading, and layerwise dtype casting.
+
+    This mixin inherits from:
+        - CPUOffloadTesterMixin: CPU and disk offloading tests
+        - GroupOffloadTesterMixin: Group offloading tests (block-level and leaf-level)
+        - LayerwiseCastingTesterMixin: Layerwise dtype casting tests
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+        - model_split_percents: List of percentages for splitting model across devices (default: [0.5, 0.7])
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Pytest mark: memory
+        Use `pytest -m "not memory"` to skip these tests
+    """
+
+    pass

tests/models/testing_utils/parallelism.py

@@ -0,0 +1,102 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+
+import pytest
+import torch
+import torch.multiprocessing as mp
+
+from diffusers.models._modeling_parallel import ContextParallelConfig
+
+from ...testing_utils import (
+    is_context_parallel,
+    require_torch_multi_accelerator,
+)
+
+
+def _context_parallel_worker(rank, world_size, model_class, init_dict, cp_dict, inputs_dict, result_queue):
+    try:
+        # Setup distributed environment
+        os.environ["MASTER_ADDR"] = "localhost"
+        os.environ["MASTER_PORT"] = "12355"
+
+        torch.distributed.init_process_group(
+            backend="nccl",
+            init_method="env://",
+            world_size=world_size,
+            rank=rank,
+        )
+        torch.cuda.set_device(rank)
+        device = torch.device(f"cuda:{rank}")
+
+        model = model_class(**init_dict)
+        model.to(device)
+        model.eval()
+
+        inputs_on_device = {}
+        for key, value in inputs_dict.items():
+            if isinstance(value, torch.Tensor):
+                inputs_on_device[key] = value.to(device)
+            else:
+                inputs_on_device[key] = value
+
+        cp_config = ContextParallelConfig(**cp_dict)
+        model.enable_parallelism(config=cp_config)
+
+        with torch.no_grad():
+            output = model(**inputs_on_device, return_dict=False)[0]
+
+        if rank == 0:
+            result_queue.put(("success", output.shape))
+
+    except Exception as e:
+        if rank == 0:
+            result_queue.put(("error", str(e)))
+    finally:
+        if torch.distributed.is_initialized():
+            torch.distributed.destroy_process_group()
+
+
+@is_context_parallel
+@require_torch_multi_accelerator
+class ContextParallelTesterMixin:
+    base_precision = 1e-3
+
+    @pytest.mark.parametrize("cp_type", ["ulysses_degree", "ring_degree"], ids=["ulysses", "ring"])
+    def test_context_parallel_inference(self, cp_type):
+        if not torch.distributed.is_available():
+            pytest.skip("torch.distributed is not available.")
+
+        if not hasattr(self.model_class, "_cp_plan") or self.model_class._cp_plan is None:
+            pytest.skip("Model does not have a _cp_plan defined for context parallel inference.")
+
+        world_size = 2
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        cp_dict = {cp_type: world_size}
+
+        ctx = mp.get_context("spawn")
+        result_queue = ctx.Queue()
+
+        mp.spawn(
+            _context_parallel_worker,
+            args=(world_size, self.model_class, init_dict, cp_dict, inputs_dict, result_queue),
+            nprocs=world_size,
+            join=True,
+        )
+
+        status, result = result_queue.get(timeout=60)
+        assert status == "success", f"Context parallel inference failed: {result}"

tests/models/testing_utils/single_file.py

@@ -0,0 +1,244 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import gc
+
+import torch
+from huggingface_hub import hf_hub_download, snapshot_download
+
+from diffusers.loaders.single_file_utils import _extract_repo_id_and_weights_name
+
+from ...testing_utils import (
+    assert_tensors_close,
+    backend_empty_cache,
+    is_single_file,
+    nightly,
+    require_torch_accelerator,
+    torch_device,
+)
+
+
+def download_single_file_checkpoint(pretrained_model_name_or_path, filename, tmpdir):
+    """Download a single file checkpoint from the Hub to a temporary directory."""
+    path = hf_hub_download(pretrained_model_name_or_path, filename=filename, local_dir=tmpdir)
+    return path
+
+
+def download_diffusers_config(pretrained_model_name_or_path, tmpdir):
+    """Download diffusers config files (excluding weights) from a repository."""
+    path = snapshot_download(
+        pretrained_model_name_or_path,
+        ignore_patterns=[
+            "**/*.ckpt",
+            "*.ckpt",
+            "**/*.bin",
+            "*.bin",
+            "**/*.pt",
+            "*.pt",
+            "**/*.safetensors",
+            "*.safetensors",
+        ],
+        allow_patterns=["**/*.json", "*.json", "*.txt", "**/*.txt"],
+        local_dir=tmpdir,
+    )
+    return path
+
+
+@nightly
+@require_torch_accelerator
+@is_single_file
+class SingleFileTesterMixin:
+    """
+    Mixin class for testing single file loading for models.
+
+    Expected class attributes:
+        - model_class: The model class to test
+        - pretrained_model_name_or_path: Hub repository ID for the pretrained model
+        - ckpt_path: Path or Hub path to the single file checkpoint
+        - subfolder: (Optional) Subfolder within the repo
+        - torch_dtype: (Optional) torch dtype to use for testing
+
+    Pytest mark: single_file
+        Use `pytest -m "not single_file"` to skip these tests
+    """
+
+    pretrained_model_name_or_path = None
+    ckpt_path = None
+
+    def setup_method(self):
+        gc.collect()
+        backend_empty_cache(torch_device)
+
+    def teardown_method(self):
+        gc.collect()
+        backend_empty_cache(torch_device)
+
+    def test_single_file_model_config(self):
+        pretrained_kwargs = {}
+        single_file_kwargs = {}
+
+        pretrained_kwargs["device"] = torch_device
+        single_file_kwargs["device"] = torch_device
+
+        if hasattr(self, "subfolder") and self.subfolder:
+            pretrained_kwargs["subfolder"] = self.subfolder
+
+        if hasattr(self, "torch_dtype") and self.torch_dtype:
+            pretrained_kwargs["torch_dtype"] = self.torch_dtype
+            single_file_kwargs["torch_dtype"] = self.torch_dtype
+
+        model = self.model_class.from_pretrained(self.pretrained_model_name_or_path, **pretrained_kwargs)
+        model_single_file = self.model_class.from_single_file(self.ckpt_path, **single_file_kwargs)
+
+        PARAMS_TO_IGNORE = ["torch_dtype", "_name_or_path", "_use_default_values", "_diffusers_version"]
+        for param_name, param_value in model_single_file.config.items():
+            if param_name in PARAMS_TO_IGNORE:
+                continue
+            assert model.config[param_name] == param_value, (
+                f"{param_name} differs between pretrained loading and single file loading: "
+                f"pretrained={model.config[param_name]}, single_file={param_value}"
+            )
+
+    def test_single_file_model_parameters(self):
+        pretrained_kwargs = {}
+        single_file_kwargs = {}
+
+        pretrained_kwargs["device"] = torch_device
+        single_file_kwargs["device"] = torch_device
+
+        if hasattr(self, "subfolder") and self.subfolder:
+            pretrained_kwargs["subfolder"] = self.subfolder
+
+        if hasattr(self, "torch_dtype") and self.torch_dtype:
+            pretrained_kwargs["torch_dtype"] = self.torch_dtype
+            single_file_kwargs["torch_dtype"] = self.torch_dtype
+
+        model = self.model_class.from_pretrained(self.pretrained_model_name_or_path, **pretrained_kwargs)
+        model_single_file = self.model_class.from_single_file(self.ckpt_path, **single_file_kwargs)
+
+        state_dict = model.state_dict()
+        state_dict_single_file = model_single_file.state_dict()
+
+        assert set(state_dict.keys()) == set(state_dict_single_file.keys()), (
+            "Model parameters keys differ between pretrained and single file loading. "
+            f"Missing in single file: {set(state_dict.keys()) - set(state_dict_single_file.keys())}. "
+            f"Extra in single file: {set(state_dict_single_file.keys()) - set(state_dict.keys())}"
+        )
+
+        for key in state_dict.keys():
+            param = state_dict[key]
+            param_single_file = state_dict_single_file[key]
+
+            assert param.shape == param_single_file.shape, (
+                f"Parameter shape mismatch for {key}: "
+                f"pretrained {param.shape} vs single file {param_single_file.shape}"
+            )
+
+            assert_tensors_close(
+                param, param_single_file, atol=1e-5, rtol=1e-5, msg=f"Parameter values differ for {key}"
+            )
+
+    def test_single_file_loading_local_files_only(self, tmp_path):
+        single_file_kwargs = {}
+
+        if hasattr(self, "torch_dtype") and self.torch_dtype:
+            single_file_kwargs["torch_dtype"] = self.torch_dtype
+
+        pretrained_model_name_or_path, weight_name = _extract_repo_id_and_weights_name(self.ckpt_path)
+        local_ckpt_path = download_single_file_checkpoint(pretrained_model_name_or_path, weight_name, str(tmp_path))
+
+        model_single_file = self.model_class.from_single_file(
+            local_ckpt_path, local_files_only=True, **single_file_kwargs
+        )
+
+        assert model_single_file is not None, "Failed to load model with local_files_only=True"
+
+    def test_single_file_loading_with_diffusers_config(self):
+        single_file_kwargs = {}
+
+        if hasattr(self, "torch_dtype") and self.torch_dtype:
+            single_file_kwargs["torch_dtype"] = self.torch_dtype
+
+        # Load with config parameter
+        model_single_file = self.model_class.from_single_file(
+            self.ckpt_path, config=self.pretrained_model_name_or_path, **single_file_kwargs
+        )
+
+        # Load pretrained for comparison
+        pretrained_kwargs = {}
+        if hasattr(self, "subfolder") and self.subfolder:
+            pretrained_kwargs["subfolder"] = self.subfolder
+        if hasattr(self, "torch_dtype") and self.torch_dtype:
+            pretrained_kwargs["torch_dtype"] = self.torch_dtype
+
+        model = self.model_class.from_pretrained(self.pretrained_model_name_or_path, **pretrained_kwargs)
+
+        # Compare configs
+        PARAMS_TO_IGNORE = ["torch_dtype", "_name_or_path", "_use_default_values", "_diffusers_version"]
+        for param_name, param_value in model_single_file.config.items():
+            if param_name in PARAMS_TO_IGNORE:
+                continue
+            assert model.config[param_name] == param_value, (
+                f"{param_name} differs: pretrained={model.config[param_name]}, single_file={param_value}"
+            )
+
+    def test_single_file_loading_with_diffusers_config_local_files_only(self, tmp_path):
+        single_file_kwargs = {}
+
+        if hasattr(self, "torch_dtype") and self.torch_dtype:
+            single_file_kwargs["torch_dtype"] = self.torch_dtype
+
+        pretrained_model_name_or_path, weight_name = _extract_repo_id_and_weights_name(self.ckpt_path)
+        local_ckpt_path = download_single_file_checkpoint(pretrained_model_name_or_path, weight_name, str(tmp_path))
+        local_diffusers_config = download_diffusers_config(self.pretrained_model_name_or_path, str(tmp_path))
+
+        model_single_file = self.model_class.from_single_file(
+            local_ckpt_path, config=local_diffusers_config, local_files_only=True, **single_file_kwargs
+        )
+
+        assert model_single_file is not None, "Failed to load model with config and local_files_only=True"
+
+    def test_single_file_loading_dtype(self):
+        for dtype in [torch.float32, torch.float16]:
+            if torch_device == "mps" and dtype == torch.bfloat16:
+                continue
+
+            model_single_file = self.model_class.from_single_file(self.ckpt_path, torch_dtype=dtype)
+
+            assert model_single_file.dtype == dtype, f"Expected dtype {dtype}, got {model_single_file.dtype}"
+
+            # Cleanup
+            del model_single_file
+            gc.collect()
+            backend_empty_cache(torch_device)
+
+    def test_checkpoint_variant_loading(self):
+        if not hasattr(self, "alternate_ckpt_paths") or not self.alternate_ckpt_paths:
+            return
+
+        for ckpt_path in self.alternate_ckpt_paths:
+            backend_empty_cache(torch_device)
+
+            single_file_kwargs = {}
+            if hasattr(self, "torch_dtype") and self.torch_dtype:
+                single_file_kwargs["torch_dtype"] = self.torch_dtype
+
+            model = self.model_class.from_single_file(ckpt_path, **single_file_kwargs)
+
+            assert model is not None, f"Failed to load checkpoint from {ckpt_path}"
+
+            del model
+            gc.collect()
+            backend_empty_cache(torch_device)

tests/models/testing_utils/training.py

@@ -0,0 +1,207 @@
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import copy
+
+import pytest
+import torch
+
+from diffusers.training_utils import EMAModel
+
+from ...testing_utils import is_training, require_torch_accelerator_with_training, torch_all_close, torch_device
+
+
+@is_training
+@require_torch_accelerator_with_training
+class TrainingTesterMixin:
+    """
+    Mixin class for testing training functionality on models.
+
+    Expected class attributes to be set by subclasses:
+        - model_class: The model class to test
+
+    Expected methods to be implemented by subclasses:
+        - get_init_dict(): Returns dict of arguments to initialize the model
+        - get_dummy_inputs(): Returns dict of inputs to pass to the model forward pass
+
+    Expected properties to be implemented by subclasses:
+        - output_shape: Tuple defining the expected output shape
+
+    Pytest mark: training
+        Use `pytest -m "not training"` to skip these tests
+    """
+
+    def test_training(self):
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+
+        model = self.model_class(**init_dict)
+        model.to(torch_device)
+        model.train()
+        output = model(**inputs_dict, return_dict=False)[0]
+
+        noise = torch.randn((output.shape[0],) + self.output_shape).to(torch_device)
+        loss = torch.nn.functional.mse_loss(output, noise)
+        loss.backward()
+
+    def test_training_with_ema(self):
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+
+        model = self.model_class(**init_dict)
+        model.to(torch_device)
+        model.train()
+        ema_model = EMAModel(model.parameters())
+
+        output = model(**inputs_dict, return_dict=False)[0]
+
+        noise = torch.randn((output.shape[0],) + self.output_shape).to(torch_device)
+        loss = torch.nn.functional.mse_loss(output, noise)
+        loss.backward()
+        ema_model.step(model.parameters())
+
+    def test_gradient_checkpointing(self):
+        if not self.model_class._supports_gradient_checkpointing:
+            pytest.skip("Gradient checkpointing is not supported.")
+
+        init_dict = self.get_init_dict()
+
+        # at init model should have gradient checkpointing disabled
+        model = self.model_class(**init_dict)
+        assert not model.is_gradient_checkpointing, "Gradient checkpointing should be disabled at init"
+
+        # check enable works
+        model.enable_gradient_checkpointing()
+        assert model.is_gradient_checkpointing, "Gradient checkpointing should be enabled"
+
+        # check disable works
+        model.disable_gradient_checkpointing()
+        assert not model.is_gradient_checkpointing, "Gradient checkpointing should be disabled"
+
+    def test_gradient_checkpointing_is_applied(self, expected_set=None):
+        if not self.model_class._supports_gradient_checkpointing:
+            pytest.skip("Gradient checkpointing is not supported.")
+
+        if expected_set is None:
+            pytest.skip("expected_set must be provided to verify gradient checkpointing is applied.")
+
+        init_dict = self.get_init_dict()
+
+        model_class_copy = copy.copy(self.model_class)
+        model = model_class_copy(**init_dict)
+        model.enable_gradient_checkpointing()
+
+        modules_with_gc_enabled = {}
+        for submodule in model.modules():
+            if hasattr(submodule, "gradient_checkpointing"):
+                assert submodule.gradient_checkpointing, f"{submodule.__class__.__name__} should have GC enabled"
+                modules_with_gc_enabled[submodule.__class__.__name__] = True
+
+        assert set(modules_with_gc_enabled.keys()) == expected_set, (
+            f"Modules with GC enabled {set(modules_with_gc_enabled.keys())} do not match expected set {expected_set}"
+        )
+        assert all(modules_with_gc_enabled.values()), "All modules should have GC enabled"
+
+    def test_gradient_checkpointing_equivalence(self, loss_tolerance=1e-5, param_grad_tol=5e-5, skip=None):
+        if not self.model_class._supports_gradient_checkpointing:
+            pytest.skip("Gradient checkpointing is not supported.")
+
+        if skip is None:
+            skip = set()
+
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+        inputs_dict_copy = copy.deepcopy(inputs_dict)
+
+        torch.manual_seed(0)
+        model = self.model_class(**init_dict)
+        model.to(torch_device)
+
+        assert not model.is_gradient_checkpointing and model.training
+
+        out = model(**inputs_dict, return_dict=False)[0]
+
+        # run the backwards pass on the model
+        model.zero_grad()
+
+        labels = torch.randn_like(out)
+        loss = (out - labels).mean()
+        loss.backward()
+
+        # re-instantiate the model now enabling gradient checkpointing
+        torch.manual_seed(0)
+        model_2 = self.model_class(**init_dict)
+        # clone model
+        model_2.load_state_dict(model.state_dict())
+        model_2.to(torch_device)
+        model_2.enable_gradient_checkpointing()
+
+        assert model_2.is_gradient_checkpointing and model_2.training
+
+        out_2 = model_2(**inputs_dict_copy, return_dict=False)[0]
+
+        # run the backwards pass on the model
+        model_2.zero_grad()
+        loss_2 = (out_2 - labels).mean()
+        loss_2.backward()
+
+        # compare the output and parameters gradients
+        assert (loss - loss_2).abs() < loss_tolerance, (
+            f"Loss difference {(loss - loss_2).abs()} exceeds tolerance {loss_tolerance}"
+        )
+
+        named_params = dict(model.named_parameters())
+        named_params_2 = dict(model_2.named_parameters())
+
+        for name, param in named_params.items():
+            if "post_quant_conv" in name:
+                continue
+            if name in skip:
+                continue
+            if param.grad is None:
+                continue
+
+            assert torch_all_close(param.grad.data, named_params_2[name].grad.data, atol=param_grad_tol), (
+                f"Gradient mismatch for {name}"
+            )
+
+    def test_mixed_precision_training(self):
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+
+        model = self.model_class(**init_dict)
+        model.to(torch_device)
+        model.train()
+
+        # Test with float16
+        if torch.device(torch_device).type != "cpu":
+            with torch.amp.autocast(device_type=torch.device(torch_device).type, dtype=torch.float16):
+                output = model(**inputs_dict, return_dict=False)[0]
+
+                noise = torch.randn((output.shape[0],) + self.output_shape).to(torch_device)
+                loss = torch.nn.functional.mse_loss(output, noise)
+
+            loss.backward()
+
+        # Test with bfloat16
+        if torch.device(torch_device).type != "cpu":
+            model.zero_grad()
+            with torch.amp.autocast(device_type=torch.device(torch_device).type, dtype=torch.bfloat16):
+                output = model(**inputs_dict, return_dict=False)[0]
+
+                noise = torch.randn((output.shape[0],) + self.output_shape).to(torch_device)
+                loss = torch.nn.functional.mse_loss(output, noise)
+
+            loss.backward()

tests/models/transformers/test_models_transformer_flux.py

@@ -13,23 +13,51 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import unittest
+from typing import Any
 
 import torch
 
 from diffusers import FluxTransformer2DModel
-from diffusers.models.attention_processor import FluxIPAdapterJointAttnProcessor2_0
 from diffusers.models.embeddings import ImageProjection
+from diffusers.models.transformers.transformer_flux import FluxIPAdapterAttnProcessor
+from diffusers.utils.torch_utils import randn_tensor
 
-from ...testing_utils import enable_full_determinism, is_peft_available, torch_device
-from ..test_modeling_common import LoraHotSwappingForModelTesterMixin, ModelTesterMixin, TorchCompileTesterMixin
+from ...testing_utils import enable_full_determinism, torch_device
+from ..testing_utils import (
+    AttentionTesterMixin,
+    BaseModelTesterConfig,
+    BitsAndBytesCompileTesterMixin,
+    BitsAndBytesTesterMixin,
+    ContextParallelTesterMixin,
+    FasterCacheTesterMixin,
+    FirstBlockCacheTesterMixin,
+    GGUFCompileTesterMixin,
+    GGUFTesterMixin,
+    IPAdapterTesterMixin,
+    LoraHotSwappingForModelTesterMixin,
+    LoraTesterMixin,
+    MemoryTesterMixin,
+    ModelOptCompileTesterMixin,
+    ModelOptTesterMixin,
+    ModelTesterMixin,
+    PyramidAttentionBroadcastTesterMixin,
+    QuantoCompileTesterMixin,
+    QuantoTesterMixin,
+    SingleFileTesterMixin,
+    TorchAoCompileTesterMixin,
+    TorchAoTesterMixin,
+    TorchCompileTesterMixin,
+    TrainingTesterMixin,
+)
 
 
 enable_full_determinism()
 
 
-def create_flux_ip_adapter_state_dict(model):
-    # "ip_adapter" (cross-attention weights)
+# TODO: This standalone function maintains backward compatibility with pipeline tests
+# (tests/pipelines/test_pipelines_common.py) and will be refactored.
+def create_flux_ip_adapter_state_dict(model) -> dict[str, dict[str, Any]]:
+    """Create a dummy IP Adapter state dict for Flux transformer testing."""
     ip_cross_attn_state_dict = {}
     key_id = 0
 
@@ -39,7 +67,7 @@ def create_flux_ip_adapter_state_dict(model):
 
         joint_attention_dim = model.config["joint_attention_dim"]
         hidden_size = model.config["num_attention_heads"] * model.config["attention_head_dim"]
-        sd = FluxIPAdapterJointAttnProcessor2_0(
+        sd = FluxIPAdapterAttnProcessor(
             hidden_size=hidden_size, cross_attention_dim=joint_attention_dim, scale=1.0
         ).state_dict()
         ip_cross_attn_state_dict.update(
@@ -50,11 +78,8 @@ def create_flux_ip_adapter_state_dict(model):
                 f"{key_id}.to_v_ip.bias": sd["to_v_ip.0.bias"],
             }
         )
-
         key_id += 1
 
-    # "image_proj" (ImageProjection layer weights)
-
     image_projection = ImageProjection(
         cross_attention_dim=model.config["joint_attention_dim"],
         image_embed_dim=(
@@ -75,57 +100,37 @@ def create_flux_ip_adapter_state_dict(model):
     )
 
     del sd
-    ip_state_dict = {}
-    ip_state_dict.update({"image_proj": ip_image_projection_state_dict, "ip_adapter": ip_cross_attn_state_dict})
-    return ip_state_dict
+    return {"image_proj": ip_image_projection_state_dict, "ip_adapter": ip_cross_attn_state_dict}
 
 
-class FluxTransformerTests(ModelTesterMixin, unittest.TestCase):
-    model_class = FluxTransformer2DModel
-    main_input_name = "hidden_states"
-    # We override the items here because the transformer under consideration is small.
-    model_split_percents = [0.7, 0.6, 0.6]
-
-    # Skip setting testing with default: AttnProcessor
-    uses_custom_attn_processor = True
+class FluxTransformerTesterConfig(BaseModelTesterConfig):
+    @property
+    def model_class(self):
+        return FluxTransformer2DModel
 
     @property
-    def dummy_input(self):
-        return self.prepare_dummy_input()
+    def pretrained_model_name_or_path(self):
+        return "hf-internal-testing/tiny-flux-pipe"
 
     @property
-    def input_shape(self):
+    def pretrained_model_kwargs(self):
+        return {"subfolder": "transformer"}
+
+    @property
+    def output_shape(self) -> tuple[int, int]:
         return (16, 4)
 
     @property
-    def output_shape(self):
+    def input_shape(self) -> tuple[int, int]:
         return (16, 4)
 
-    def prepare_dummy_input(self, height=4, width=4):
-        batch_size = 1
-        num_latent_channels = 4
-        num_image_channels = 3
-        sequence_length = 48
-        embedding_dim = 32
-
-        hidden_states = torch.randn((batch_size, height * width, num_latent_channels)).to(torch_device)
-        encoder_hidden_states = torch.randn((batch_size, sequence_length, embedding_dim)).to(torch_device)
-        pooled_prompt_embeds = torch.randn((batch_size, embedding_dim)).to(torch_device)
-        text_ids = torch.randn((sequence_length, num_image_channels)).to(torch_device)
-        image_ids = torch.randn((height * width, num_image_channels)).to(torch_device)
-        timestep = torch.tensor([1.0]).to(torch_device).expand(batch_size)
+    @property
+    def generator(self):
+        return torch.Generator("cpu").manual_seed(0)
 
+    def get_init_dict(self) -> dict[str, int | list[int]]:
+        """Return Flux model initialization arguments."""
         return {
-            "hidden_states": hidden_states,
-            "encoder_hidden_states": encoder_hidden_states,
-            "img_ids": image_ids,
-            "txt_ids": text_ids,
-            "pooled_projections": pooled_prompt_embeds,
-            "timestep": timestep,
-        }
-
-    def prepare_init_args_and_inputs_for_common(self):
-        init_dict = {
             "patch_size": 1,
             "in_channels": 4,
             "num_layers": 1,
@@ -137,11 +142,32 @@ class FluxTransformerTests(ModelTesterMixin, unittest.TestCase):
             "axes_dims_rope": [4, 4, 8],
         }
 
-        inputs_dict = self.dummy_input
-        return init_dict, inputs_dict
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        batch_size = 1
+        height = width = 4
+        num_latent_channels = 4
+        num_image_channels = 3
+        sequence_length = 48
+        embedding_dim = 32
 
+        return {
+            "hidden_states": randn_tensor((batch_size, height * width, num_latent_channels), generator=self.generator),
+            "encoder_hidden_states": randn_tensor(
+                (batch_size, sequence_length, embedding_dim), generator=self.generator
+            ),
+            "pooled_projections": randn_tensor((batch_size, embedding_dim), generator=self.generator),
+            "img_ids": randn_tensor((height * width, num_image_channels), generator=self.generator),
+            "txt_ids": randn_tensor((sequence_length, num_image_channels), generator=self.generator),
+            "timestep": torch.tensor([1.0]).to(torch_device).expand(batch_size),
+        }
+
+
+class TestFluxTransformer(FluxTransformerTesterConfig, ModelTesterMixin):
     def test_deprecated_inputs_img_txt_ids_3d(self):
-        init_dict, inputs_dict = self.prepare_init_args_and_inputs_for_common()
+        """Test that deprecated 3D img_ids and txt_ids still work."""
+        init_dict = self.get_init_dict()
+        inputs_dict = self.get_dummy_inputs()
+
         model = self.model_class(**init_dict)
         model.to(torch_device)
         model.eval()
@@ -162,63 +188,267 @@ class FluxTransformerTests(ModelTesterMixin, unittest.TestCase):
         with torch.no_grad():
             output_2 = model(**inputs_dict).to_tuple()[0]
 
-        self.assertEqual(output_1.shape, output_2.shape)
-        self.assertTrue(
-            torch.allclose(output_1, output_2, atol=1e-5),
-            msg="output with deprecated inputs (img_ids and txt_ids as 3d torch tensors) are not equal as them as 2d inputs",
+        assert output_1.shape == output_2.shape
+        assert torch.allclose(output_1, output_2, atol=1e-5), (
+            "output with deprecated inputs (img_ids and txt_ids as 3d torch tensors) "
+            "are not equal as them as 2d inputs"
         )
 
-    def test_gradient_checkpointing_is_applied(self):
-        expected_set = {"FluxTransformer2DModel"}
-        super().test_gradient_checkpointing_is_applied(expected_set=expected_set)
 
-    # The test exists for cases like
-    # https://github.com/huggingface/diffusers/issues/11874
-    @unittest.skipIf(not is_peft_available(), "Only with PEFT")
-    def test_lora_exclude_modules(self):
-        from peft import LoraConfig, get_peft_model_state_dict, inject_adapter_in_model, set_peft_model_state_dict
+class TestFluxTransformerMemory(FluxTransformerTesterConfig, MemoryTesterMixin):
+    """Memory optimization tests for Flux Transformer."""
 
-        lora_rank = 4
-        target_module = "single_transformer_blocks.0.proj_out"
-        adapter_name = "foo"
-        init_dict, _ = self.prepare_init_args_and_inputs_for_common()
-        model = self.model_class(**init_dict).to(torch_device)
+    pass
 
-        state_dict = model.state_dict()
-        target_mod_shape = state_dict[f"{target_module}.weight"].shape
-        lora_state_dict = {
-            f"{target_module}.lora_A.weight": torch.ones(lora_rank, target_mod_shape[1]) * 22,
-            f"{target_module}.lora_B.weight": torch.ones(target_mod_shape[0], lora_rank) * 33,
+
+class TestFluxTransformerTraining(FluxTransformerTesterConfig, TrainingTesterMixin):
+    """Training tests for Flux Transformer."""
+
+    pass
+
+
+class TestFluxTransformerAttention(FluxTransformerTesterConfig, AttentionTesterMixin):
+    """Attention processor tests for Flux Transformer."""
+
+    pass
+
+
+class TestFluxTransformerContextParallel(FluxTransformerTesterConfig, ContextParallelTesterMixin):
+    """Context Parallel inference tests for Flux Transformer"""
+
+    pass
+
+
+class TestFluxTransformerIPAdapter(FluxTransformerTesterConfig, IPAdapterTesterMixin):
+    """IP Adapter tests for Flux Transformer."""
+
+    ip_adapter_processor_cls = FluxIPAdapterAttnProcessor
+
+    def modify_inputs_for_ip_adapter(self, model, inputs_dict):
+        torch.manual_seed(0)
+        # Create dummy image embeds for IP adapter
+        cross_attention_dim = getattr(model.config, "joint_attention_dim", 32)
+        image_embeds = torch.randn(1, 1, cross_attention_dim).to(torch_device)
+
+        inputs_dict.update({"joint_attention_kwargs": {"ip_adapter_image_embeds": image_embeds}})
+
+        return inputs_dict
+
+    def create_ip_adapter_state_dict(self, model: Any) -> dict[str, dict[str, Any]]:
+        return create_flux_ip_adapter_state_dict(model)
+
+
+class TestFluxTransformerLoRA(FluxTransformerTesterConfig, LoraTesterMixin):
+    """LoRA adapter tests for Flux Transformer."""
+
+    pass
+
+
+class TestFluxTransformerLoRAHotSwap(FluxTransformerTesterConfig, LoraHotSwappingForModelTesterMixin):
+    """LoRA hot-swapping tests for Flux Transformer."""
+
+    different_shapes_for_compilation = [(4, 4), (4, 8), (8, 8)]
+
+    def get_dummy_inputs(self, height: int = 4, width: int = 4) -> dict[str, torch.Tensor]:
+        """Override to support dynamic height/width for LoRA hotswap tests."""
+        batch_size = 1
+        num_latent_channels = 4
+        num_image_channels = 3
+        sequence_length = 24
+        embedding_dim = 8
+
+        return {
+            "hidden_states": randn_tensor((batch_size, height * width, num_latent_channels)),
+            "encoder_hidden_states": randn_tensor((batch_size, sequence_length, embedding_dim)),
+            "pooled_projections": randn_tensor((batch_size, embedding_dim)),
+            "img_ids": randn_tensor((height * width, num_image_channels)),
+            "txt_ids": randn_tensor((sequence_length, num_image_channels)),
+            "timestep": torch.tensor([1.0]).to(torch_device).expand(batch_size),
         }
-        # Passing exclude_modules should no longer be necessary (or even passing target_modules, for that matter).
-        config = LoraConfig(
-            r=lora_rank, target_modules=["single_transformer_blocks.0.proj_out"], exclude_modules=["proj_out"]
-        )
-        inject_adapter_in_model(config, model, adapter_name=adapter_name, state_dict=lora_state_dict)
-        set_peft_model_state_dict(model, lora_state_dict, adapter_name)
-        retrieved_lora_state_dict = get_peft_model_state_dict(model, adapter_name=adapter_name)
-        assert len(retrieved_lora_state_dict) == len(lora_state_dict)
-        assert (retrieved_lora_state_dict["single_transformer_blocks.0.proj_out.lora_A.weight"] == 22).all()
-        assert (retrieved_lora_state_dict["single_transformer_blocks.0.proj_out.lora_B.weight"] == 33).all()
 
 
-class FluxTransformerCompileTests(TorchCompileTesterMixin, unittest.TestCase):
-    model_class = FluxTransformer2DModel
+class TestFluxTransformerCompile(FluxTransformerTesterConfig, TorchCompileTesterMixin):
     different_shapes_for_compilation = [(4, 4), (4, 8), (8, 8)]
 
-    def prepare_init_args_and_inputs_for_common(self):
-        return FluxTransformerTests().prepare_init_args_and_inputs_for_common()
+    def get_dummy_inputs(self, height: int = 4, width: int = 4) -> dict[str, torch.Tensor]:
+        """Override to support dynamic height/width for compilation tests."""
+        batch_size = 1
+        num_latent_channels = 4
+        num_image_channels = 3
+        sequence_length = 24
+        embedding_dim = 8
 
-    def prepare_dummy_input(self, height, width):
-        return FluxTransformerTests().prepare_dummy_input(height=height, width=width)
+        return {
+            "hidden_states": randn_tensor((batch_size, height * width, num_latent_channels)),
+            "encoder_hidden_states": randn_tensor((batch_size, sequence_length, embedding_dim)),
+            "pooled_projections": randn_tensor((batch_size, embedding_dim)),
+            "img_ids": randn_tensor((height * width, num_image_channels)),
+            "txt_ids": randn_tensor((sequence_length, num_image_channels)),
+            "timestep": torch.tensor([1.0]).to(torch_device).expand(batch_size),
+        }
 
 
-class FluxTransformerLoRAHotSwapTests(LoraHotSwappingForModelTesterMixin, unittest.TestCase):
-    model_class = FluxTransformer2DModel
-    different_shapes_for_compilation = [(4, 4), (4, 8), (8, 8)]
+class TestFluxSingleFile(FluxTransformerTesterConfig, SingleFileTesterMixin):
+    ckpt_path = "https://huggingface.co/black-forest-labs/FLUX.1-dev/blob/main/flux1-dev.safetensors"
+    alternate_keys_ckpt_paths = ["https://huggingface.co/Comfy-Org/flux1-dev/blob/main/flux1-dev-fp8.safetensors"]
+    pretrained_model_name_or_path = "black-forest-labs/FLUX.1-dev"
+    subfolder = "transformer"
+    pass
 
-    def prepare_init_args_and_inputs_for_common(self):
-        return FluxTransformerTests().prepare_init_args_and_inputs_for_common()
 
-    def prepare_dummy_input(self, height, width):
-        return FluxTransformerTests().prepare_dummy_input(height=height, width=width)
+class TestFluxTransformerBitsAndBytes(FluxTransformerTesterConfig, BitsAndBytesTesterMixin):
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerQuanto(FluxTransformerTesterConfig, QuantoTesterMixin):
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerTorchAo(FluxTransformerTesterConfig, TorchAoTesterMixin):
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerGGUF(FluxTransformerTesterConfig, GGUFTesterMixin):
+    gguf_filename = "https://huggingface.co/city96/FLUX.1-dev-gguf/blob/main/flux1-dev-Q8_0.gguf"
+
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerModelOpt(FluxTransformerTesterConfig, ModelOptTesterMixin):
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerBitsAndBytesCompile(FluxTransformerTesterConfig, BitsAndBytesCompileTesterMixin):
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerQuantoCompile(FluxTransformerTesterConfig, QuantoCompileTesterMixin):
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerTorchAoCompile(FluxTransformerTesterConfig, TorchAoCompileTesterMixin):
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerGGUFCompile(FluxTransformerTesterConfig, GGUFCompileTesterMixin):
+    gguf_filename = "https://huggingface.co/city96/FLUX.1-dev-gguf/blob/main/flux1-dev-Q8_0.gguf"
+
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerModelOptCompile(FluxTransformerTesterConfig, ModelOptCompileTesterMixin):
+    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:
+        return {
+            "hidden_states": randn_tensor((1, 4096, 64)),
+            "encoder_hidden_states": randn_tensor((1, 512, 4096)),
+            "pooled_projections": randn_tensor((1, 768)),
+            "timestep": torch.tensor([1.0]).to(torch_device),
+            "img_ids": randn_tensor((4096, 3)),
+            "txt_ids": randn_tensor((512, 3)),
+            "guidance": torch.tensor([3.5]).to(torch_device),
+        }
+
+
+class TestFluxTransformerPABCache(FluxTransformerTesterConfig, PyramidAttentionBroadcastTesterMixin):
+    """PyramidAttentionBroadcast cache tests for Flux Transformer."""
+
+    pass
+
+
+class TestFluxTransformerFBCCache(FluxTransformerTesterConfig, FirstBlockCacheTesterMixin):
+    """FirstBlockCache tests for Flux Transformer."""
+
+    pass
+
+
+class TestFluxTransformerFasterCache(FluxTransformerTesterConfig, FasterCacheTesterMixin):
+    """FasterCache tests for Flux Transformer."""
+
+    # Flux is guidance distilled, so we can test at model level without CFG batch handling
+    FASTER_CACHE_CONFIG = {
+        "spatial_attention_block_skip_range": 2,
+        "spatial_attention_timestep_skip_range": (-1, 901),
+        "tensor_format": "BCHW",
+        "is_guidance_distilled": True,
+    }

tests/testing_utils.py

@@ -38,6 +38,7 @@ from diffusers.utils.import_utils import (
     is_gguf_available,
     is_kernels_available,
     is_note_seq_available,
+    is_nvidia_modelopt_available,
     is_onnx_available,
     is_opencv_available,
     is_optimum_quanto_available,
@@ -130,6 +131,59 @@ def torch_all_close(a, b, *args, **kwargs):
     return True
 
 
+def assert_tensors_close(
+    actual: "torch.Tensor",
+    expected: "torch.Tensor",
+    atol: float = 1e-5,
+    rtol: float = 1e-5,
+    msg: str = "",
+) -> None:
+    """
+    Assert that two tensors are close within tolerance.
+
+    Uses the same formula as torch.allclose: |actual - expected| <= atol + rtol * |expected|
+    Provides concise, actionable error messages without dumping full tensors.
+
+    Args:
+        actual: The actual tensor from the computation.
+        expected: The expected tensor to compare against.
+        atol: Absolute tolerance.
+        rtol: Relative tolerance.
+        msg: Optional message prefix for the assertion error.
+
+    Raises:
+        AssertionError: If tensors have different shapes or values exceed tolerance.
+
+    Example:
+        >>> assert_tensors_close(output, expected_output, atol=1e-5, rtol=1e-5, msg="Forward pass")
+    """
+    if not is_torch_available():
+        raise ValueError("PyTorch needs to be installed to use this function.")
+
+    if actual.shape != expected.shape:
+        raise AssertionError(f"{msg} Shape mismatch: actual {actual.shape} vs expected {expected.shape}")
+
+    if not torch.allclose(actual, expected, atol=atol, rtol=rtol):
+        abs_diff = (actual - expected).abs()
+        max_diff = abs_diff.max().item()
+
+        flat_idx = abs_diff.argmax().item()
+        max_idx = tuple(torch.unravel_index(torch.tensor(flat_idx), actual.shape).tolist())
+
+        threshold = atol + rtol * expected.abs()
+        mismatched = (abs_diff > threshold).sum().item()
+        total = actual.numel()
+
+        raise AssertionError(
+            f"{msg}\n"
+            f"Tensors not close! Mismatched elements: {mismatched}/{total} ({100 * mismatched / total:.1f}%)\n"
+            f"  Max diff: {max_diff:.6e} at index {max_idx}\n"
+            f"  Actual:   {actual.flatten()[flat_idx].item():.6e}\n"
+            f"  Expected: {expected.flatten()[flat_idx].item():.6e}\n"
+            f"  atol: {atol:.6e}, rtol: {rtol:.6e}"
+        )
+
+
 def numpy_cosine_similarity_distance(a, b):
     similarity = np.dot(a, b) / (norm(a) * norm(b))
     distance = 1.0 - similarity.mean()
@@ -241,7 +295,6 @@ def parse_flag_from_env(key, default=False):
 
 _run_slow_tests = parse_flag_from_env("RUN_SLOW", default=False)
 _run_nightly_tests = parse_flag_from_env("RUN_NIGHTLY", default=False)
-_run_compile_tests = parse_flag_from_env("RUN_COMPILE", default=False)
 
 
 def floats_tensor(shape, scale=1.0, rng=None, name=None):
@@ -282,12 +335,155 @@ def nightly(test_case):
 
 def is_torch_compile(test_case):
     """
-    Decorator marking a test that runs compile tests in the diffusers CI.
-
-    Compile tests are skipped by default. Set the RUN_COMPILE environment variable to a truthy value to run them.
-
+    Decorator marking a test as a torch.compile test. These tests can be filtered using:
+        pytest -m "not compile" to skip
+        pytest -m compile to run only these tests
     """
-    return pytest.mark.skipif(not _run_compile_tests, reason="test is torch compile")(test_case)
+    return pytest.mark.compile(test_case)
+
+
+def is_single_file(test_case):
+    """
+    Decorator marking a test as a single file loading test. These tests can be filtered using:
+        pytest -m "not single_file" to skip
+        pytest -m single_file to run only these tests
+    """
+    return pytest.mark.single_file(test_case)
+
+
+def is_lora(test_case):
+    """
+    Decorator marking a test as a LoRA test. These tests can be filtered using:
+        pytest -m "not lora" to skip
+        pytest -m lora to run only these tests
+    """
+    return pytest.mark.lora(test_case)
+
+
+def is_ip_adapter(test_case):
+    """
+    Decorator marking a test as an IP Adapter test. These tests can be filtered using:
+        pytest -m "not ip_adapter" to skip
+        pytest -m ip_adapter to run only these tests
+    """
+    return pytest.mark.ip_adapter(test_case)
+
+
+def is_training(test_case):
+    """
+    Decorator marking a test as a training test. These tests can be filtered using:
+        pytest -m "not training" to skip
+        pytest -m training to run only these tests
+    """
+    return pytest.mark.training(test_case)
+
+
+def is_attention(test_case):
+    """
+    Decorator marking a test as an attention test. These tests can be filtered using:
+        pytest -m "not attention" to skip
+        pytest -m attention to run only these tests
+    """
+    return pytest.mark.attention(test_case)
+
+
+def is_memory(test_case):
+    """
+    Decorator marking a test as a memory optimization test. These tests can be filtered using:
+        pytest -m "not memory" to skip
+        pytest -m memory to run only these tests
+    """
+    return pytest.mark.memory(test_case)
+
+
+def is_cpu_offload(test_case):
+    """
+    Decorator marking a test as a CPU offload test. These tests can be filtered using:
+        pytest -m "not cpu_offload" to skip
+        pytest -m cpu_offload to run only these tests
+    """
+    return pytest.mark.cpu_offload(test_case)
+
+
+def is_group_offload(test_case):
+    """
+    Decorator marking a test as a group offload test. These tests can be filtered using:
+        pytest -m "not group_offload" to skip
+        pytest -m group_offload to run only these tests
+    """
+    return pytest.mark.group_offload(test_case)
+
+
+def is_quantization(test_case):
+    """
+    Decorator marking a test as a quantization test. These tests can be filtered using:
+        pytest -m "not quantization" to skip
+        pytest -m quantization to run only these tests
+    """
+    return pytest.mark.quantization(test_case)
+
+
+def is_bitsandbytes(test_case):
+    """
+    Decorator marking a test as a BitsAndBytes quantization test. These tests can be filtered using:
+        pytest -m "not bitsandbytes" to skip
+        pytest -m bitsandbytes to run only these tests
+    """
+    return pytest.mark.bitsandbytes(test_case)
+
+
+def is_quanto(test_case):
+    """
+    Decorator marking a test as a Quanto quantization test. These tests can be filtered using:
+        pytest -m "not quanto" to skip
+        pytest -m quanto to run only these tests
+    """
+    return pytest.mark.quanto(test_case)
+
+
+def is_torchao(test_case):
+    """
+    Decorator marking a test as a TorchAO quantization test. These tests can be filtered using:
+        pytest -m "not torchao" to skip
+        pytest -m torchao to run only these tests
+    """
+    return pytest.mark.torchao(test_case)
+
+
+def is_gguf(test_case):
+    """
+    Decorator marking a test as a GGUF quantization test. These tests can be filtered using:
+        pytest -m "not gguf" to skip
+        pytest -m gguf to run only these tests
+    """
+    return pytest.mark.gguf(test_case)
+
+
+def is_modelopt(test_case):
+    """
+    Decorator marking a test as a NVIDIA ModelOpt quantization test. These tests can be filtered using:
+        pytest -m "not modelopt" to skip
+        pytest -m modelopt to run only these tests
+    """
+    return pytest.mark.modelopt(test_case)
+
+
+def is_context_parallel(test_case):
+    """
+    Decorator marking a test as a context parallel inference test. These tests can be filtered using:
+        pytest -m "not context_parallel" to skip
+        pytest -m context_parallel to run only these tests
+    """
+    return pytest.mark.context_parallel(test_case)
+
+
+def is_cache(test_case):
+    """
+    Decorator marking a test as a cache test. These tests can be filtered using:
+        pytest -m "not cache" to skip
+        pytest -m cache to run only these tests
+    """
+    return pytest.mark.cache(test_case)
 
 
 def require_torch(test_case):
@@ -650,6 +846,19 @@ def require_kernels_version_greater_or_equal(kernels_version):
     return decorator
 
 
+def require_modelopt_version_greater_or_equal(modelopt_version):
+    def decorator(test_case):
+        correct_nvidia_modelopt_version = is_nvidia_modelopt_available() and version.parse(
+            version.parse(importlib.metadata.version("modelopt")).base_version
+        ) >= version.parse(modelopt_version)
+        return pytest.mark.skipif(
+            not correct_nvidia_modelopt_version,
+            reason=f"Test requires modelopt with version greater than {modelopt_version}.",
+        )(test_case)
+
+    return decorator
+
+
 def deprecate_after_peft_backend(test_case):
     """
     Decorator marking a test that will be skipped after PEFT backend

utils/generate_model_tests.py

@@ -0,0 +1,567 @@
+#!/usr/bin/env python
+# coding=utf-8
+# Copyright 2025 HuggingFace Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Utility script to generate test suites for diffusers model classes.
+
+Usage:
+    python utils/generate_model_tests.py src/diffusers/models/transformers/transformer_flux.py
+
+This will analyze the model file and generate a test file with appropriate
+test classes based on the model's mixins and attributes.
+"""
+
+import argparse
+import ast
+import sys
+from pathlib import Path
+
+
+MIXIN_TO_TESTER = {
+    "ModelMixin": "ModelTesterMixin",
+    "PeftAdapterMixin": "LoraTesterMixin",
+}
+
+ATTRIBUTE_TO_TESTER = {
+    "_cp_plan": "ContextParallelTesterMixin",
+    "_supports_gradient_checkpointing": "TrainingTesterMixin",
+}
+
+ALWAYS_INCLUDE_TESTERS = [
+    "ModelTesterMixin",
+    "MemoryTesterMixin",
+    "TorchCompileTesterMixin",
+]
+
+# Attention-related class names that indicate the model uses attention
+ATTENTION_INDICATORS = {
+    "AttentionMixin",
+    "AttentionModuleMixin",
+}
+
+OPTIONAL_TESTERS = [
+    # Quantization testers
+    ("BitsAndBytesTesterMixin", "bnb"),
+    ("QuantoTesterMixin", "quanto"),
+    ("TorchAoTesterMixin", "torchao"),
+    ("GGUFTesterMixin", "gguf"),
+    ("ModelOptTesterMixin", "modelopt"),
+    # Quantization compile testers
+    ("BitsAndBytesCompileTesterMixin", "bnb_compile"),
+    ("QuantoCompileTesterMixin", "quanto_compile"),
+    ("TorchAoCompileTesterMixin", "torchao_compile"),
+    ("GGUFCompileTesterMixin", "gguf_compile"),
+    ("ModelOptCompileTesterMixin", "modelopt_compile"),
+    # Cache testers
+    ("PyramidAttentionBroadcastTesterMixin", "pab_cache"),
+    ("FirstBlockCacheTesterMixin", "fbc_cache"),
+    ("FasterCacheTesterMixin", "faster_cache"),
+    # Other testers
+    ("SingleFileTesterMixin", "single_file"),
+    ("IPAdapterTesterMixin", "ip_adapter"),
+]
+
+
+class ModelAnalyzer(ast.NodeVisitor):
+    def __init__(self):
+        self.model_classes = []
+        self.current_class = None
+        self.imports = set()
+
+    def visit_Import(self, node: ast.Import):
+        for alias in node.names:
+            self.imports.add(alias.name.split(".")[-1])
+        self.generic_visit(node)
+
+    def visit_ImportFrom(self, node: ast.ImportFrom):
+        for alias in node.names:
+            self.imports.add(alias.name)
+        self.generic_visit(node)
+
+    def visit_ClassDef(self, node: ast.ClassDef):
+        base_names = []
+        for base in node.bases:
+            if isinstance(base, ast.Name):
+                base_names.append(base.id)
+            elif isinstance(base, ast.Attribute):
+                base_names.append(base.attr)
+
+        if "ModelMixin" in base_names:
+            class_info = {
+                "name": node.name,
+                "bases": base_names,
+                "attributes": {},
+                "has_forward": False,
+                "init_params": [],
+            }
+
+            for item in node.body:
+                if isinstance(item, ast.Assign):
+                    for target in item.targets:
+                        if isinstance(target, ast.Name):
+                            attr_name = target.id
+                            if attr_name.startswith("_"):
+                                class_info["attributes"][attr_name] = self._get_value(item.value)
+
+                elif isinstance(item, ast.FunctionDef):
+                    if item.name == "forward":
+                        class_info["has_forward"] = True
+                        class_info["forward_params"] = self._extract_func_params(item)
+                    elif item.name == "__init__":
+                        class_info["init_params"] = self._extract_func_params(item)
+
+            self.model_classes.append(class_info)
+
+        self.generic_visit(node)
+
+    def _extract_func_params(self, func_node: ast.FunctionDef) -> list[dict]:
+        params = []
+        args = func_node.args
+
+        num_defaults = len(args.defaults)
+        num_args = len(args.args)
+        first_default_idx = num_args - num_defaults
+
+        for i, arg in enumerate(args.args):
+            if arg.arg == "self":
+                continue
+
+            param_info = {"name": arg.arg, "type": None, "default": None}
+
+            if arg.annotation:
+                param_info["type"] = self._get_annotation_str(arg.annotation)
+
+            default_idx = i - first_default_idx
+            if default_idx >= 0 and default_idx < len(args.defaults):
+                param_info["default"] = self._get_value(args.defaults[default_idx])
+
+            params.append(param_info)
+
+        return params
+
+    def _get_annotation_str(self, node) -> str:
+        if isinstance(node, ast.Name):
+            return node.id
+        elif isinstance(node, ast.Constant):
+            return repr(node.value)
+        elif isinstance(node, ast.Subscript):
+            base = self._get_annotation_str(node.value)
+            if isinstance(node.slice, ast.Tuple):
+                args = ", ".join(self._get_annotation_str(el) for el in node.slice.elts)
+            else:
+                args = self._get_annotation_str(node.slice)
+            return f"{base}[{args}]"
+        elif isinstance(node, ast.Attribute):
+            return f"{self._get_annotation_str(node.value)}.{node.attr}"
+        elif isinstance(node, ast.BinOp) and isinstance(node.op, ast.BitOr):
+            left = self._get_annotation_str(node.left)
+            right = self._get_annotation_str(node.right)
+            return f"{left} | {right}"
+        elif isinstance(node, ast.Tuple):
+            return ", ".join(self._get_annotation_str(el) for el in node.elts)
+        return "Any"
+
+    def _get_value(self, node):
+        if isinstance(node, ast.Constant):
+            return node.value
+        elif isinstance(node, ast.Name):
+            if node.id == "None":
+                return None
+            elif node.id == "True":
+                return True
+            elif node.id == "False":
+                return False
+            return node.id
+        elif isinstance(node, ast.List):
+            return [self._get_value(el) for el in node.elts]
+        elif isinstance(node, ast.Dict):
+            return {self._get_value(k): self._get_value(v) for k, v in zip(node.keys, node.values)}
+        return "<complex>"
+
+
+def analyze_model_file(filepath: str) -> tuple[list[dict], set[str]]:
+    with open(filepath) as f:
+        source = f.read()
+
+    tree = ast.parse(source)
+    analyzer = ModelAnalyzer()
+    analyzer.visit(tree)
+
+    return analyzer.model_classes, analyzer.imports
+
+
+def determine_testers(model_info: dict, include_optional: list[str], imports: set[str]) -> list[str]:
+    testers = list(ALWAYS_INCLUDE_TESTERS)
+
+    for base in model_info["bases"]:
+        if base in MIXIN_TO_TESTER:
+            tester = MIXIN_TO_TESTER[base]
+            if tester not in testers:
+                testers.append(tester)
+
+    for attr, tester in ATTRIBUTE_TO_TESTER.items():
+        if attr in model_info["attributes"]:
+            value = model_info["attributes"][attr]
+            if value is not None and value is not False:
+                if tester not in testers:
+                    testers.append(tester)
+
+    if "_cp_plan" in model_info["attributes"] and model_info["attributes"]["_cp_plan"] is not None:
+        if "ContextParallelTesterMixin" not in testers:
+            testers.append("ContextParallelTesterMixin")
+
+    # Include AttentionTesterMixin if the model imports attention-related classes
+    if imports & ATTENTION_INDICATORS:
+        testers.append("AttentionTesterMixin")
+
+    for tester, flag in OPTIONAL_TESTERS:
+        if flag in include_optional:
+            if tester not in testers:
+                testers.append(tester)
+
+    return testers
+
+
+def generate_config_class(model_info: dict, model_name: str) -> str:
+    class_name = f"{model_name}TesterConfig"
+    model_class = model_info["name"]
+    forward_params = model_info.get("forward_params", [])
+    init_params = model_info.get("init_params", [])
+
+    lines = [
+        f"class {class_name}:",
+        f"    model_class = {model_class}",
+        '    pretrained_model_name_or_path = ""',
+        '    pretrained_model_kwargs = {"subfolder": "transformer"}',
+        "",
+        "    @property",
+        "    def generator(self):",
+        '        return torch.Generator("cpu").manual_seed(0)',
+        "",
+        "    def get_init_dict(self) -> dict[str, int | list[int]]:",
+    ]
+
+    if init_params:
+        lines.append("        # __init__ parameters:")
+        for param in init_params:
+            type_str = f": {param['type']}" if param["type"] else ""
+            default_str = f" = {param['default']}" if param["default"] is not None else ""
+            lines.append(f"        #   {param['name']}{type_str}{default_str}")
+
+    lines.extend(
+        [
+            "        return {}",
+            "",
+            "    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:",
+        ]
+    )
+
+    if forward_params:
+        lines.append("        # forward() parameters:")
+        for param in forward_params:
+            type_str = f": {param['type']}" if param["type"] else ""
+            default_str = f" = {param['default']}" if param["default"] is not None else ""
+            lines.append(f"        #   {param['name']}{type_str}{default_str}")
+
+    lines.extend(
+        [
+            "        # TODO: Fill in dummy inputs",
+            "        return {}",
+            "",
+            "    @property",
+            "    def input_shape(self) -> tuple[int, ...]:",
+            "        return (1, 1)",
+            "",
+            "    @property",
+            "    def output_shape(self) -> tuple[int, ...]:",
+            "        return (1, 1)",
+        ]
+    )
+
+    return "\n".join(lines)
+
+
+def generate_test_class(model_name: str, config_class: str, tester: str) -> str:
+    tester_short = tester.replace("TesterMixin", "")
+    class_name = f"Test{model_name}{tester_short}"
+
+    lines = [f"class {class_name}({config_class}, {tester}):"]
+
+    if tester == "TorchCompileTesterMixin":
+        lines.extend(
+            [
+                "    different_shapes_for_compilation = [(4, 4), (4, 8), (8, 8)]",
+                "",
+                "    def get_dummy_inputs(self, height: int = 4, width: int = 4) -> dict[str, torch.Tensor]:",
+                "        # TODO: Implement dynamic input generation",
+                "        return {}",
+            ]
+        )
+    elif tester == "IPAdapterTesterMixin":
+        lines.extend(
+            [
+                "    ip_adapter_processor_cls = None  # TODO: Set processor class",
+                "",
+                "    def modify_inputs_for_ip_adapter(self, model, inputs_dict):",
+                "        # TODO: Add IP adapter image embeds to inputs",
+                "        return inputs_dict",
+                "",
+                "    def create_ip_adapter_state_dict(self, model):",
+                "        # TODO: Create IP adapter state dict",
+                "        return {}",
+            ]
+        )
+    elif tester == "SingleFileTesterMixin":
+        lines.extend(
+            [
+                '    ckpt_path = ""  # TODO: Set checkpoint path',
+                "    alternate_keys_ckpt_paths = []",
+                '    pretrained_model_name_or_path = ""',
+                '    subfolder = "transformer"',
+            ]
+        )
+    elif tester == "GGUFTesterMixin":
+        lines.extend(
+            [
+                '    gguf_filename = ""  # TODO: Set GGUF filename',
+                "",
+                "    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:",
+                "        # TODO: Override with larger inputs for quantization tests",
+                "        return {}",
+            ]
+        )
+    elif tester in ["BitsAndBytesTesterMixin", "QuantoTesterMixin", "TorchAoTesterMixin", "ModelOptTesterMixin"]:
+        lines.extend(
+            [
+                "    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:",
+                "        # TODO: Override with larger inputs for quantization tests",
+                "        return {}",
+            ]
+        )
+    elif tester in [
+        "BitsAndBytesCompileTesterMixin",
+        "QuantoCompileTesterMixin",
+        "TorchAoCompileTesterMixin",
+        "ModelOptCompileTesterMixin",
+    ]:
+        lines.extend(
+            [
+                "    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:",
+                "        # TODO: Override with larger inputs for quantization compile tests",
+                "        return {}",
+            ]
+        )
+    elif tester == "GGUFCompileTesterMixin":
+        lines.extend(
+            [
+                '    gguf_filename = ""  # TODO: Set GGUF filename',
+                "",
+                "    def get_dummy_inputs(self) -> dict[str, torch.Tensor]:",
+                "        # TODO: Override with larger inputs for quantization compile tests",
+                "        return {}",
+            ]
+        )
+    elif tester in [
+        "PyramidAttentionBroadcastTesterMixin",
+        "FirstBlockCacheTesterMixin",
+        "FasterCacheTesterMixin",
+    ]:
+        lines.append("    pass")
+    elif tester == "LoraHotSwappingForModelTesterMixin":
+        lines.extend(
+            [
+                "    different_shapes_for_compilation = [(4, 4), (4, 8), (8, 8)]",
+                "",
+                "    def get_dummy_inputs(self, height: int = 4, width: int = 4) -> dict[str, torch.Tensor]:",
+                "        # TODO: Implement dynamic input generation",
+                "        return {}",
+            ]
+        )
+    else:
+        lines.append("    pass")
+
+    return "\n".join(lines)
+
+
+def generate_test_file(model_info: dict, model_filepath: str, include_optional: list[str], imports: set[str]) -> str:
+    model_name = model_info["name"].replace("2DModel", "").replace("3DModel", "").replace("Model", "")
+    testers = determine_testers(model_info, include_optional, imports)
+    tester_imports = sorted(set(testers) - {"LoraHotSwappingForModelTesterMixin"})
+
+    lines = [
+        "# coding=utf-8",
+        "# Copyright 2025 HuggingFace Inc.",
+        "#",
+        '# Licensed under the Apache License, Version 2.0 (the "License");',
+        "# you may not use this file except in compliance with the License.",
+        "# You may obtain a copy of the License at",
+        "#",
+        "#     http://www.apache.org/licenses/LICENSE-2.0",
+        "#",
+        "# Unless required by applicable law or agreed to in writing, software",
+        '# distributed under the License is distributed on an "AS IS" BASIS,',
+        "# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.",
+        "# See the License for the specific language governing permissions and",
+        "# limitations under the License.",
+        "",
+        "import torch",
+        "",
+        f"from diffusers import {model_info['name']}",
+        "from diffusers.utils.torch_utils import randn_tensor",
+        "",
+        "from ...testing_utils import enable_full_determinism, torch_device",
+    ]
+
+    if "LoraTesterMixin" in testers:
+        lines.append("from ..test_modeling_common import LoraHotSwappingForModelTesterMixin")
+
+    lines.extend(
+        [
+            "from ..testing_utils import (",
+            *[f"    {tester}," for tester in sorted(tester_imports)],
+            ")",
+            "",
+            "",
+            "enable_full_determinism()",
+            "",
+            "",
+        ]
+    )
+
+    config_class = f"{model_name}TesterConfig"
+    lines.append(generate_config_class(model_info, model_name))
+    lines.append("")
+    lines.append("")
+
+    for tester in testers:
+        lines.append(generate_test_class(model_name, config_class, tester))
+        lines.append("")
+        lines.append("")
+
+    if "LoraTesterMixin" in testers:
+        lines.append(generate_test_class(model_name, config_class, "LoraHotSwappingForModelTesterMixin"))
+        lines.append("")
+        lines.append("")
+
+    return "\n".join(lines).rstrip() + "\n"
+
+
+def get_test_output_path(model_filepath: str) -> str:
+    path = Path(model_filepath)
+    model_filename = path.stem
+
+    if "transformers" in path.parts:
+        return f"tests/models/transformers/test_models_{model_filename}.py"
+    elif "unets" in path.parts:
+        return f"tests/models/unets/test_models_{model_filename}.py"
+    elif "autoencoders" in path.parts:
+        return f"tests/models/autoencoders/test_models_{model_filename}.py"
+    else:
+        return f"tests/models/test_models_{model_filename}.py"
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Generate test suite for a diffusers model class")
+    parser.add_argument(
+        "model_filepath",
+        type=str,
+        help="Path to the model file (e.g., src/diffusers/models/transformers/transformer_flux.py)",
+    )
+    parser.add_argument(
+        "--output", "-o", type=str, default=None, help="Output file path (default: auto-generated based on model path)"
+    )
+    parser.add_argument(
+        "--include",
+        "-i",
+        type=str,
+        nargs="*",
+        default=[],
+        choices=[
+            "bnb",
+            "quanto",
+            "torchao",
+            "gguf",
+            "modelopt",
+            "bnb_compile",
+            "quanto_compile",
+            "torchao_compile",
+            "gguf_compile",
+            "modelopt_compile",
+            "pab_cache",
+            "fbc_cache",
+            "faster_cache",
+            "single_file",
+            "ip_adapter",
+            "all",
+        ],
+        help="Optional testers to include",
+    )
+    parser.add_argument(
+        "--class-name",
+        "-c",
+        type=str,
+        default=None,
+        help="Specific model class to generate tests for (default: first model class found)",
+    )
+    parser.add_argument("--dry-run", action="store_true", help="Print generated code without writing to file")
+
+    args = parser.parse_args()
+
+    if not Path(args.model_filepath).exists():
+        print(f"Error: File not found: {args.model_filepath}", file=sys.stderr)
+        sys.exit(1)
+
+    model_classes, imports = analyze_model_file(args.model_filepath)
+
+    if not model_classes:
+        print(f"Error: No model classes found in {args.model_filepath}", file=sys.stderr)
+        sys.exit(1)
+
+    if args.class_name:
+        model_info = next((m for m in model_classes if m["name"] == args.class_name), None)
+        if not model_info:
+            available = [m["name"] for m in model_classes]
+            print(f"Error: Class '{args.class_name}' not found. Available: {available}", file=sys.stderr)
+            sys.exit(1)
+    else:
+        model_info = model_classes[0]
+        if len(model_classes) > 1:
+            print(f"Multiple model classes found, using: {model_info['name']}", file=sys.stderr)
+            print("Use --class-name to specify a different class", file=sys.stderr)
+
+    include_optional = args.include
+    if "all" in include_optional:
+        include_optional = [flag for _, flag in OPTIONAL_TESTERS]
+
+    generated_code = generate_test_file(model_info, args.model_filepath, include_optional, imports)
+
+    if args.dry_run:
+        print(generated_code)
+    else:
+        output_path = args.output or get_test_output_path(args.model_filepath)
+        output_dir = Path(output_path).parent
+        output_dir.mkdir(parents=True, exist_ok=True)
+
+        with open(output_path, "w") as f:
+            f.write(generated_code)
+
+        print(f"Generated test file: {output_path}")
+        print(f"Model class: {model_info['name']}")
+        print(f"Detected attributes: {list(model_info['attributes'].keys())}")
+
+
+if __name__ == "__main__":
+    main()