test: replacing tmpdir with tmp_path in tests_pytorch/helpers (#…

…19643)

* refactored tmpdir from the tests_pytorch/helpers dir
* Update tests/tests_pytorch/helpers/test_datasets.py

---------

Co-authored-by: awaelchli <aedu.waelchli@gmail.com>

tests/tests_pytorch/helpers/test_datasets.py

@@ -24,7 +24,7 @@
     ("dataset_cls", "args"),
     [(MNIST, {"root": _PATH_DATASETS}), (TrialMNIST, {"root": _PATH_DATASETS}), (AverageDataset, {})],
 )
-def test_pickling_dataset_mnist(tmpdir, dataset_cls, args):
+def test_pickling_dataset_mnist(dataset_cls, args):
     mnist = dataset_cls(**args)
 
     mnist_pickled = pickle.dumps(mnist)

tests/tests_pytorch/helpers/test_models.py

@@ -35,11 +35,11 @@
         pytest.param(RegressDataModule, RegressionModel, marks=RunIf(sklearn=True, onnx=True)),
     ],
 )
-def test_models(tmpdir, data_class, model_class):
+def test_models(tmp_path, data_class, model_class):
     """Test simple models."""
     dm = data_class() if data_class else data_class
     model = model_class()
-    trainer = Trainer(default_root_dir=tmpdir, max_epochs=1)
+    trainer = Trainer(default_root_dir=tmp_path, max_epochs=1)
 
     trainer.fit(model, datamodule=dm)
 
@@ -48,4 +48,4 @@ def test_models(tmpdir, data_class, model_class):
 
     model.to_torchscript()
     if data_class:
-        model.to_onnx(os.path.join(tmpdir, "my-model.onnx"), input_sample=dm.sample)
+        model.to_onnx(os.path.join(tmp_path, "my-model.onnx"), input_sample=dm.sample)