tests/models/transformers/test_models_dit_transformer2d.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 DiTTransformer2DModel, Transformer2DModel

from ...testing_utils import (
    enable_full_determinism,
    floats_tensor,
    slow,
    torch_device,
)
from ..test_modeling_common import ModelTesterMixin


enable_full_determinism()


class DiTTransformer2DModelTests(ModelTesterMixin, unittest.TestCase):
    model_class = DiTTransformer2DModel
    main_input_name = "hidden_states"

    @property
    def dummy_input(self):
        batch_size = 4
        in_channels = 4
        sample_size = 8
        scheduler_num_train_steps = 1000
        num_class_labels = 4

        hidden_states = floats_tensor((batch_size, in_channels, sample_size, sample_size)).to(torch_device)
        timesteps = torch.randint(0, scheduler_num_train_steps, size=(batch_size,)).to(torch_device)
        class_label_ids = torch.randint(0, num_class_labels, size=(batch_size,)).to(torch_device)

        return {"hidden_states": hidden_states, "timestep": timesteps, "class_labels": class_label_ids}

    @property
    def input_shape(self):
        return (4, 8, 8)

    @property
    def output_shape(self):
        return (8, 8, 8)

    def prepare_init_args_and_inputs_for_common(self):
        init_dict = {
            "in_channels": 4,
            "out_channels": 8,
            "activation_fn": "gelu-approximate",
            "num_attention_heads": 2,
            "attention_head_dim": 4,
            "attention_bias": True,
            "num_layers": 1,
            "norm_type": "ada_norm_zero",
            "num_embeds_ada_norm": 8,
            "patch_size": 2,
            "sample_size": 8,
        }
        inputs_dict = self.dummy_input
        return init_dict, inputs_dict

    def test_output(self):
        super().test_output(
            expected_output_shape=(self.dummy_input[self.main_input_name].shape[0],) + self.output_shape
        )

    def test_correct_class_remapping_from_dict_config(self):
        init_dict, _ = self.prepare_init_args_and_inputs_for_common()
        model = Transformer2DModel.from_config(init_dict)
        assert isinstance(model, DiTTransformer2DModel)

    def test_gradient_checkpointing_is_applied(self):
        expected_set = {"DiTTransformer2DModel"}
        super().test_gradient_checkpointing_is_applied(expected_set=expected_set)

    def test_effective_gradient_checkpointing(self):
        super().test_effective_gradient_checkpointing(loss_tolerance=1e-4)

    def test_correct_class_remapping_from_pretrained_config(self):
        config = DiTTransformer2DModel.load_config("facebook/DiT-XL-2-256", subfolder="transformer")
        model = Transformer2DModel.from_config(config)
        assert isinstance(model, DiTTransformer2DModel)

    @slow
    def test_correct_class_remapping(self):
        model = Transformer2DModel.from_pretrained("facebook/DiT-XL-2-256", subfolder="transformer")
        assert isinstance(model, DiTTransformer2DModel)