diffusers/tests/models/transformers/test_models_transformer_sd3.py

# 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 unittest

import torch

from diffusers import SD3Transformer2DModel
from diffusers.utils.import_utils import is_xformers_available
from diffusers.utils.testing_utils import (
    enable_full_determinism,
    torch_device,
)

from ..test_modeling_common import ModelTesterMixin


enable_full_determinism()


class SD3TransformerTests(ModelTesterMixin, unittest.TestCase):
    model_class = SD3Transformer2DModel
    main_input_name = "hidden_states"
    model_split_percents = [0.8, 0.8, 0.9]

    @property
    def dummy_input(self):
        batch_size = 2
        num_channels = 4
        height = width = embedding_dim = 32
        pooled_embedding_dim = embedding_dim * 2
        sequence_length = 154

        hidden_states = torch.randn((batch_size, num_channels, height, width)).to(torch_device)
        encoder_hidden_states = torch.randn((batch_size, sequence_length, embedding_dim)).to(torch_device)
        pooled_prompt_embeds = torch.randn((batch_size, pooled_embedding_dim)).to(torch_device)
        timestep = torch.randint(0, 1000, size=(batch_size,)).to(torch_device)

        return {
            "hidden_states": hidden_states,
            "encoder_hidden_states": encoder_hidden_states,
            "pooled_projections": pooled_prompt_embeds,
            "timestep": timestep,
        }

    @property
    def input_shape(self):
        return (4, 32, 32)

    @property
    def output_shape(self):
        return (4, 32, 32)

    def prepare_init_args_and_inputs_for_common(self):
        init_dict = {
            "sample_size": 32,
            "patch_size": 1,
            "in_channels": 4,
            "num_layers": 4,
            "attention_head_dim": 8,
            "num_attention_heads": 4,
            "caption_projection_dim": 32,
            "joint_attention_dim": 32,
            "pooled_projection_dim": 64,
            "out_channels": 4,
            "pos_embed_max_size": 96,
            "dual_attention_layers": (),
            "qk_norm": None,
        }
        inputs_dict = self.dummy_input
        return init_dict, inputs_dict

    @unittest.skipIf(
        torch_device != "cuda" or not is_xformers_available(),
        reason="XFormers attention is only available with CUDA and `xformers` installed",
    )
    def test_xformers_enable_works(self):
        init_dict, inputs_dict = self.prepare_init_args_and_inputs_for_common()
        model = self.model_class(**init_dict)

        model.enable_xformers_memory_efficient_attention()

        assert model.transformer_blocks[0].attn.processor.__class__.__name__ == "XFormersJointAttnProcessor", (
            "xformers is not enabled"
        )

    @unittest.skip("SD3Transformer2DModel uses a dedicated attention processor. This test doesn't apply")
    def test_set_attn_processor_for_determinism(self):
        pass

    def test_gradient_checkpointing_is_applied(self):
        expected_set = {"SD3Transformer2DModel"}
        super().test_gradient_checkpointing_is_applied(expected_set=expected_set)


class SD35TransformerTests(ModelTesterMixin, unittest.TestCase):
    model_class = SD3Transformer2DModel
    main_input_name = "hidden_states"
    model_split_percents = [0.8, 0.8, 0.9]

    @property
    def dummy_input(self):
        batch_size = 2
        num_channels = 4
        height = width = embedding_dim = 32
        pooled_embedding_dim = embedding_dim * 2
        sequence_length = 154

        hidden_states = torch.randn((batch_size, num_channels, height, width)).to(torch_device)
        encoder_hidden_states = torch.randn((batch_size, sequence_length, embedding_dim)).to(torch_device)
        pooled_prompt_embeds = torch.randn((batch_size, pooled_embedding_dim)).to(torch_device)
        timestep = torch.randint(0, 1000, size=(batch_size,)).to(torch_device)

        return {
            "hidden_states": hidden_states,
            "encoder_hidden_states": encoder_hidden_states,
            "pooled_projections": pooled_prompt_embeds,
            "timestep": timestep,
        }

    @property
    def input_shape(self):
        return (4, 32, 32)

    @property
    def output_shape(self):
        return (4, 32, 32)

    def prepare_init_args_and_inputs_for_common(self):
        init_dict = {
            "sample_size": 32,
            "patch_size": 1,
            "in_channels": 4,
            "num_layers": 4,
            "attention_head_dim": 8,
            "num_attention_heads": 4,
            "caption_projection_dim": 32,
            "joint_attention_dim": 32,
            "pooled_projection_dim": 64,
            "out_channels": 4,
            "pos_embed_max_size": 96,
            "dual_attention_layers": (0,),
            "qk_norm": "rms_norm",
        }
        inputs_dict = self.dummy_input
        return init_dict, inputs_dict

    @unittest.skipIf(
        torch_device != "cuda" or not is_xformers_available(),
        reason="XFormers attention is only available with CUDA and `xformers` installed",
    )
    def test_xformers_enable_works(self):
        init_dict, inputs_dict = self.prepare_init_args_and_inputs_for_common()
        model = self.model_class(**init_dict)

        model.enable_xformers_memory_efficient_attention()

        assert model.transformer_blocks[0].attn.processor.__class__.__name__ == "XFormersJointAttnProcessor", (
            "xformers is not enabled"
        )

    @unittest.skip("SD3Transformer2DModel uses a dedicated attention processor. This test doesn't apply")
    def test_set_attn_processor_for_determinism(self):
        pass

    def test_gradient_checkpointing_is_applied(self):
        expected_set = {"SD3Transformer2DModel"}
        super().test_gradient_checkpointing_is_applied(expected_set=expected_set)

    def test_skip_layers(self):
        init_dict, inputs_dict = self.prepare_init_args_and_inputs_for_common()
        model = self.model_class(**init_dict).to(torch_device)

        # Forward pass without skipping layers
        output_full = model(**inputs_dict).sample

        # Forward pass with skipping layers 0 (since there's only one layer in this test setup)
        inputs_dict_with_skip = inputs_dict.copy()
        inputs_dict_with_skip["skip_layers"] = [0]
        output_skip = model(**inputs_dict_with_skip).sample

        # Check that the outputs are different
        self.assertFalse(
            torch.allclose(output_full, output_skip, atol=1e-5), "Outputs should differ when layers are skipped"
        )

        # Check that the outputs have the same shape
        self.assertEqual(output_full.shape, output_skip.shape, "Outputs should have the same shape")