add tests for Coco (#3416)

Co-authored-by: Francisco Massa <fvsmassa@gmail.com>

test/test_datasets.py

@@ -21,6 +21,7 @@ import pickle
 from torchvision import datasets
 import torch
 import shutil
+import json
 
 
 try:
@@ -839,5 +840,70 @@ class VOCDetectionTestCase(VOCSegmentationTestCase):
             self.assertEqual(object, info["annotation"])
 
 
+class CocoDetectionTestCase(datasets_utils.ImageDatasetTestCase):
+    DATASET_CLASS = datasets.CocoDetection
+    FEATURE_TYPES = (PIL.Image.Image, list)
+
+    REQUIRED_PACKAGES = ("pycocotools",)
+
+    def inject_fake_data(self, tmpdir, config):
+        tmpdir = pathlib.Path(tmpdir)
+
+        num_images = 3
+        num_annotations_per_image = 2
+
+        image_folder = tmpdir / "images"
+        files = datasets_utils.create_image_folder(
+            tmpdir, name="images", file_name_fn=lambda idx: f"{idx:012d}.jpg", num_examples=num_images
+        )
+        file_names = [file.relative_to(image_folder) for file in files]
+
+        annotation_folder = tmpdir / "annotations"
+        os.makedirs(annotation_folder)
+        annotation_file, info = self._create_annotation_file(annotation_folder, file_names, num_annotations_per_image)
+
+        info["num_examples"] = num_images
+        return (str(image_folder), str(annotation_file)), info
+
+    def _create_annotation_file(self, root, file_names, num_annotations_per_image):
+        image_ids = [int(file_name.stem) for file_name in file_names]
+        images = [dict(file_name=str(file_name), id=id) for file_name, id in zip(file_names, image_ids)]
+
+        annotations, info = self._create_annotations(image_ids, num_annotations_per_image)
+
+        content = dict(images=images, annotations=annotations)
+        return self._create_json(root, "annotations.json", content), info
+
+    def _create_annotations(self, image_ids, num_annotations_per_image):
+        annotations = datasets_utils.combinations_grid(
+            image_id=image_ids, bbox=([1.0, 2.0, 3.0, 4.0],) * num_annotations_per_image
+        )
+        for id, annotation in enumerate(annotations):
+            annotation["id"] = id
+        return annotations, dict()
+
+    def _create_json(self, root, name, content):
+        file = pathlib.Path(root) / name
+        with open(file, "w") as fh:
+            json.dump(content, fh)
+        return file
+
+
+class CocoCaptionsTestCase(CocoDetectionTestCase):
+    DATASET_CLASS = datasets.CocoCaptions
+
+    def _create_annotations(self, image_ids, num_annotations_per_image):
+        captions = [str(idx) for idx in range(num_annotations_per_image)]
+        annotations = datasets_utils.combinations_grid(image_id=image_ids, caption=captions)
+        for id, annotation in enumerate(annotations):
+            annotation["id"] = id
+        return annotations, dict(captions=captions)
+
+    def test_captions(self):
+        with self.create_dataset() as (dataset, info):
+            _, captions = dataset[0]
+            self.assertEqual(tuple(captions), tuple(info["captions"]))
+
+
 if __name__ == "__main__":
     unittest.main()