Port test/test_datasets.py to use pytest (#4215)

* Port test_datasets.py to use pytest

* A better replacement of self.assertSequenceEqual

* Migrate from equality check to identity check

test/datasets_utils.py

@@ -14,6 +14,7 @@
 
 import PIL
 import PIL.Image
+import pytest
 import torch
 import torchvision.datasets
 import torchvision.io
@@ -519,18 +520,18 @@ def _maybe_apply_patches(self, patchers):
             yield mocks
 
     def test_not_found_or_corrupted(self):
-        with self.assertRaises((FileNotFoundError, RuntimeError)):
+        with pytest.raises((FileNotFoundError, RuntimeError)):
             with self.create_dataset(inject_fake_data=False):
                 pass
 
     def test_smoke(self):
         with self.create_dataset() as (dataset, _):
-            self.assertIsInstance(dataset, torchvision.datasets.VisionDataset)
+            assert isinstance(dataset, torchvision.datasets.VisionDataset)
 
     @test_all_configs
     def test_str_smoke(self, config):
         with self.create_dataset(config) as (dataset, _):
-            self.assertIsInstance(str(dataset), str)
+            assert isinstance(str(dataset), str)
 
     @test_all_configs
     def test_feature_types(self, config):
@@ -540,23 +541,21 @@ def test_feature_types(self, config):
             if len(self.FEATURE_TYPES) > 1:
                 actual = len(example)
                 expected = len(self.FEATURE_TYPES)
-                self.assertEqual(
-                    actual,
-                    expected,
-                    f"The number of the returned features does not match the the number of elements in FEATURE_TYPES: "
-                    f"{actual} != {expected}",
-                )
+                assert (
+                    actual == expected
+                ), "The number of the returned features does not match the the number of elements in FEATURE_TYPES: "
+                f"{actual} != {expected}"
             else:
                 example = (example,)
 
             for idx, (feature, expected_feature_type) in enumerate(zip(example, self.FEATURE_TYPES)):
                 with self.subTest(idx=idx):
-                    self.assertIsInstance(feature, expected_feature_type)
+                    assert isinstance(feature, expected_feature_type)
 
     @test_all_configs
     def test_num_examples(self, config):
         with self.create_dataset(config) as (dataset, info):
-            self.assertEqual(len(dataset), info["num_examples"])
+            assert len(dataset) == info["num_examples"]
 
     @test_all_configs
     def test_transforms(self, config):

test/test_datasets.py

@@ -16,6 +16,7 @@
 import PIL
 import datasets_utils
 import numpy as np
+import pytest
 import torch
 import torch.nn.functional as F
 from torchvision import datasets
@@ -88,20 +89,20 @@ def inject_fake_data(self, tmpdir, config):
     def test_folds(self):
         for fold in range(10):
             with self.create_dataset(split="train", folds=fold) as (dataset, _):
-                self.assertEqual(len(dataset), fold + 1)
+                assert len(dataset) == fold + 1
 
     def test_unlabeled(self):
         with self.create_dataset(split="unlabeled") as (dataset, _):
             labels = [dataset[idx][1] for idx in range(len(dataset))]
-            self.assertTrue(all(label == -1 for label in labels))
+            assert all(label == -1 for label in labels)
 
     def test_invalid_folds1(self):
-        with self.assertRaises(ValueError):
+        with pytest.raises(ValueError):
             with self.create_dataset(folds=10):
                 pass
 
     def test_invalid_folds2(self):
-        with self.assertRaises(ValueError):
+        with pytest.raises(ValueError):
             with self.create_dataset(folds="0"):
                 pass
 
@@ -167,23 +168,19 @@ def test_combined_targets(self):
 
         actual = len(individual_targets)
         expected = len(combined_targets)
-        self.assertEqual(
-            actual,
-            expected,
-            f"The number of the returned combined targets does not match the the number targets if requested "
-            f"individually: {actual} != {expected}",
-        )
+        assert (
+            actual == expected
+        ), "The number of the returned combined targets does not match the the number targets if requested "
+        f"individually: {actual} != {expected}",
 
         for target_type, combined_target, individual_target in zip(target_types, combined_targets, individual_targets):
             with self.subTest(target_type=target_type):
                 actual = type(combined_target)
                 expected = type(individual_target)
-                self.assertIs(
-                    actual,
-                    expected,
-                    f"Type of the combined target does not match the type of the corresponding individual target: "
-                    f"{actual} is not {expected}",
-                )
+                assert (
+                    actual is expected
+                ), "Type of the combined target does not match the type of the corresponding individual target: "
+                f"{actual} is not {expected}",
 
 
 class Caltech256TestCase(datasets_utils.ImageDatasetTestCase):
@@ -363,26 +360,26 @@ def test_combined_targets(self):
 
         with self.create_dataset(target_type=target_types) as (dataset, _):
             output = dataset[0]
-            self.assertTrue(isinstance(output, tuple))
-            self.assertTrue(len(output) == 2)
-            self.assertTrue(isinstance(output[0], PIL.Image.Image))
-            self.assertTrue(isinstance(output[1], tuple))
-            self.assertTrue(len(output[1]) == 3)
-            self.assertTrue(isinstance(output[1][0], PIL.Image.Image))  # semantic
-            self.assertTrue(isinstance(output[1][1], dict))  # polygon
-            self.assertTrue(isinstance(output[1][2], PIL.Image.Image))  # color
+            assert isinstance(output, tuple)
+            assert len(output) == 2
+            assert isinstance(output[0], PIL.Image.Image)
+            assert isinstance(output[1], tuple)
+            assert len(output[1]) == 3
+            assert isinstance(output[1][0], PIL.Image.Image)  # semantic
+            assert isinstance(output[1][1], dict)  # polygon
+            assert isinstance(output[1][2], PIL.Image.Image)  # color
 
     def test_feature_types_target_color(self):
         with self.create_dataset(target_type='color') as (dataset, _):
             color_img, color_target = dataset[0]
-            self.assertTrue(isinstance(color_img, PIL.Image.Image))
-            self.assertTrue(np.array(color_target).shape[2] == 4)
+            assert isinstance(color_img, PIL.Image.Image)
+            assert np.array(color_target).shape[2] == 4
 
     def test_feature_types_target_polygon(self):
         with self.create_dataset(target_type='polygon') as (dataset, info):
             polygon_img, polygon_target = dataset[0]
-            self.assertTrue(isinstance(polygon_img, PIL.Image.Image))
-            self.assertEqual(polygon_target, info['expected_polygon_target'])
+            assert isinstance(polygon_img, PIL.Image.Image)
+            (polygon_target, info['expected_polygon_target'])
 
 
 class ImageNetTestCase(datasets_utils.ImageDatasetTestCase):
@@ -469,7 +466,7 @@ def test_class_to_idx(self):
         with self.create_dataset() as (dataset, info):
             expected = {category: label for label, category in enumerate(info["categories"])}
             actual = dataset.class_to_idx
-            self.assertEqual(actual, expected)
+            assert actual == expected
 
 
 class CIFAR100(CIFAR10TestCase):
@@ -573,33 +570,29 @@ def test_combined_targets(self):
 
         actual = len(individual_targets)
         expected = len(combined_targets)
-        self.assertEqual(
-            actual,
-            expected,
-            f"The number of the returned combined targets does not match the the number targets if requested "
-            f"individually: {actual} != {expected}",
-        )
+        assert (
+            actual == expected
+        ), "The number of the returned combined targets does not match the the number targets if requested "
+        f"individually: {actual} != {expected}",
 
         for target_type, combined_target, individual_target in zip(target_types, combined_targets, individual_targets):
             with self.subTest(target_type=target_type):
                 actual = type(combined_target)
                 expected = type(individual_target)
-                self.assertIs(
-                    actual,
-                    expected,
-                    f"Type of the combined target does not match the type of the corresponding individual target: "
-                    f"{actual} is not {expected}",
-                )
+                assert (
+                    actual is expected
+                ), "Type of the combined target does not match the type of the corresponding individual target: "
+                f"{actual} is not {expected}",
 
     def test_no_target(self):
         with self.create_dataset(target_type=[]) as (dataset, _):
             _, target = dataset[0]
 
-        self.assertIsNone(target)
+        assert target is None
 
     def test_attr_names(self):
         with self.create_dataset() as (dataset, info):
-            self.assertEqual(tuple(dataset.attr_names), info["attr_names"])
+            assert tuple(dataset.attr_names) == info["attr_names"]
 
 
 class VOCSegmentationTestCase(datasets_utils.ImageDatasetTestCase):
@@ -704,16 +697,16 @@ def test_annotations(self):
         with self.create_dataset() as (dataset, info):
             _, target = dataset[0]
 
-            self.assertIn("annotation", target)
+            assert "annotation" in target
             annotation = target["annotation"]
 
-            self.assertIn("object", annotation)
+            assert "object" in annotation
             objects = annotation["object"]
 
-            self.assertEqual(len(objects), 1)
+            assert len(objects) == 1
             object = objects[0]
 
-            self.assertEqual(object, info["annotation"])
+            assert object == info["annotation"]
 
 
 class CocoDetectionTestCase(datasets_utils.ImageDatasetTestCase):
@@ -789,7 +782,7 @@ def _create_annotations(self, image_ids, num_annotations_per_image):
     def test_captions(self):
         with self.create_dataset() as (dataset, info):
             _, captions = dataset[0]
-            self.assertEqual(tuple(captions), tuple(info["captions"]))
+            assert tuple(captions) == tuple(info["captions"])
 
 
 class UCF101TestCase(datasets_utils.VideoDatasetTestCase):
@@ -940,7 +933,7 @@ def _create_lmdb(self, root, cls):
     def test_not_found_or_corrupted(self):
         # LSUN does not raise built-in exception, but a custom one. It is expressive enough to not 'cast' it to
         # RuntimeError or FileNotFoundError that are normally checked by this test.
-        with self.assertRaises(datasets_utils.lazy_importer.lmdb.Error):
+        with pytest.raises(datasets_utils.lazy_importer.lmdb.Error):
             super().test_not_found_or_corrupted()
 
 
@@ -1369,7 +1362,8 @@ def _create_captions(self, num_captions_per_image):
     def test_captions(self):
         with self.create_dataset() as (dataset, info):
             _, captions = dataset[0]
-            self.assertSequenceEqual(captions, info["captions"])
+            assert len(captions) == len(info["captions"])
+            assert all([a == b for a, b in zip(captions, info["captions"])])
 
 
 class Flickr30kTestCase(Flickr8kTestCase):
@@ -1513,7 +1507,7 @@ def test_num_examples_test50k(self):
         with self.create_dataset(what="test50k") as (dataset, info):
             # Since the split 'test50k' selects all images beginning from the index 10000, we subtract the number of
             # created examples by this.
-            self.assertEqual(len(dataset), info["num_examples"] - 10000)
+            assert len(dataset) == info["num_examples"] - 10000
 
 
 class DatasetFolderTestCase(datasets_utils.ImageDatasetTestCase):
@@ -1578,12 +1572,13 @@ def test_is_valid_file(self, config):
         with self.create_dataset(
                 config, extensions=None, is_valid_file=lambda file: pathlib.Path(file).suffix[1:] in extensions
         ) as (dataset, info):
-            self.assertEqual(len(dataset), info["num_examples"])
+            assert len(dataset) == info["num_examples"]
 
     @datasets_utils.test_all_configs
     def test_classes(self, config):
         with self.create_dataset(config) as (dataset, info):
-            self.assertSequenceEqual(dataset.classes, info["classes"])
+            assert len(dataset.classes) == len(info["classes"])
+            assert all([a == b for a, b in zip(dataset.classes, info["classes"])])
 
 
 class ImageFolderTestCase(datasets_utils.ImageDatasetTestCase):
@@ -1603,7 +1598,8 @@ def inject_fake_data(self, tmpdir, config):
     @datasets_utils.test_all_configs
     def test_classes(self, config):
         with self.create_dataset(config) as (dataset, info):
-            self.assertSequenceEqual(dataset.classes, info["classes"])
+            assert len(dataset.classes) == len(info["classes"])
+            assert all([a == b for a, b in zip(dataset.classes, info["classes"])])
 
 
 class KittiTestCase(datasets_utils.ImageDatasetTestCase):
@@ -1742,15 +1738,15 @@ def inject_fake_data(self, tmpdir, config):
     def test_classes(self):
         classes = list(map(lambda x: x[0], self._CATEGORIES_CONTENT))
         with self.create_dataset() as (dataset, _):
-            self.assertEqual(dataset.classes, classes)
+            assert dataset.classes == classes
 
     def test_class_to_idx(self):
         class_to_idx = dict(self._CATEGORIES_CONTENT)
         with self.create_dataset() as (dataset, _):
-            self.assertEqual(dataset.class_to_idx, class_to_idx)
+            assert dataset.class_to_idx == class_to_idx
 
     def test_images_download_preexisting(self):
-        with self.assertRaises(RuntimeError):
+        with pytest.raises(RuntimeError):
             with self.create_dataset({'download': True}):
                 pass
 
@@ -1788,9 +1784,9 @@ def test_targets(self):
         with self.create_dataset(target_type=target_types, version="2021_valid") as (dataset, _):
             items = [d[1] for d in dataset]
             for i, item in enumerate(items):
-                self.assertEqual(dataset.category_name("kingdom", item[0]), "Akingdom")
-                self.assertEqual(dataset.category_name("phylum", item[1]), f"{i // 3}phylum")
-                self.assertEqual(item[6], i // 3)
+                assert dataset.category_name("kingdom", item[0]) == "Akingdom"
+                assert dataset.category_name("phylum", item[1]) == f"{i // 3}phylum"
+                assert item[6] == i // 3
 
 
 if __name__ == "__main__":