Fix cross-platform unit test failures

Keep diffusers model detection available when pipeline imports fail under the minimum Transformers dependency set. Give cold distributed and native extension tests platform-appropriate time budgets.

Signed-off-by: Johannes Rausch <jrausch@nvidia.com>

Author: j-rausch

modelopt/torch/export/diffusers_utils.py

@@ -32,15 +32,22 @@
 ModelMixin: type[Any] | None
 try:  # diffusers is optional for LTX-2 export paths
     from diffusers import DiffusionPipeline as _DiffusionPipeline
-    from diffusers import ModelMixin as _ModelMixin
 
     DiffusionPipeline = _DiffusionPipeline
-    ModelMixin = _ModelMixin
-    _HAS_DIFFUSERS = True
 except Exception:  # pragma: no cover
     DiffusionPipeline = None
+
+try:
+    try:
+        from diffusers import ModelMixin as _ModelMixin
+    except ImportError:  # older diffusers releases do not export ModelMixin at package level
+        from diffusers.models.modeling_utils import ModelMixin as _ModelMixin
+
+    ModelMixin = _ModelMixin
+except Exception:  # pragma: no cover
     ModelMixin = None
-    _HAS_DIFFUSERS = False
+
+_HAS_DIFFUSERS = DiffusionPipeline is not None or ModelMixin is not None
 
 TI2VidTwoStagesPipeline: type[Any] | None
 try:  # optional for LTX-2 export paths

tests/unit/onnx/quantization/test_qdq_utils.py

@@ -705,6 +705,7 @@ def create_test_model_with_int4_dq_matmul():
 class TestColumnMajorTransformation:
     """Test suite for column-major storage transformation functions."""
 
+    @pytest.mark.timeout(180)
     def test_column_major_transformation_graph_structure(self):
         """Test that column-major transformation produces correct graph structure.
 

tests/unit/torch/quantization/test_dist.py

@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import pytest
 import torch
 import torch.distributed as dist
 from _test_utils.torch.distributed.utils import spawn_multiprocess_job
@@ -43,5 +44,6 @@ def forward_loop(model):
     dist.destroy_process_group()
 
 
+@pytest.mark.timeout(120)
 def test_data_parallel(skip_on_windows):
     spawn_multiprocess_job(2, _test_data_parallel_helper, backend="gloo")