update

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 +1,509 @@
+#!/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 = [
+    ("BitsAndBytesTesterMixin", "bnb"),
+    ("QuantoTesterMixin", "quanto"),
+    ("TorchAoTesterMixin", "torchao"),
+    ("GGUFTesterMixin", "gguf"),
+    ("ModelOptTesterMixin", "modelopt"),
+    ("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 == "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=["compile", "bnb", "quanto", "torchao", "gguf", "modelopt", "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()