add download tests for VOC (#2834)

Author: pmeier

test/test_datasets_download.py

@@ -46,15 +46,20 @@ def inner_wrapper(request, *args, **kwargs):
 
 
 @contextlib.contextmanager
-def log_download_attempts(urls_and_md5s=None, patch=True, patch_auxiliaries=None):
+def log_download_attempts(
+    urls_and_md5s=None,
+    patch=True,
+    download_url_target="torchvision.datasets.utils.download_url",
+    patch_auxiliaries=None,
+):
     if urls_and_md5s is None:
         urls_and_md5s = set()
     if patch_auxiliaries is None:
         patch_auxiliaries = patch
 
     with contextlib.ExitStack() as stack:
         download_url_mock = stack.enter_context(
-            unittest.mock.patch("torchvision.datasets.utils.download_url", wraps=None if patch else download_url)
+            unittest.mock.patch(download_url_target, wraps=None if patch else download_url)
         )
         if patch_auxiliaries:
             # download_and_extract_archive
@@ -127,13 +132,9 @@ def make_download_configs(urls_and_md5s, name=None):
     ]
 
 
-def collect_download_configs(dataset_loader, name):
-    try:
-        with log_download_attempts() as urls_and_md5s:
-            dataset_loader()
-    except Exception:
-        pass
-
+def collect_download_configs(dataset_loader, name, **kwargs):
+    with contextlib.suppress(Exception), log_download_attempts(**kwargs) as urls_and_md5s:
+        dataset_loader()
     return make_download_configs(urls_and_md5s, name)
 
 
@@ -164,6 +165,17 @@ def cifar100():
     return collect_download_configs(lambda: datasets.CIFAR10(".", download=True), "CIFAR100")
 
 
+def voc():
+    download_configs = []
+    for year in ("2007", "2007-test", "2008", "2009", "2010", "2011", "2012"):
+        with contextlib.suppress(Exception), log_download_attempts(
+            download_url_target="torchvision.datasets.voc.download_url"
+        ) as urls_and_md5s:
+            datasets.VOCSegmentation(".", year=year, download=True)
+        download_configs.extend(make_download_configs(urls_and_md5s, f"VOC, {year}"))
+    return download_configs
+
+
 def make_parametrize_kwargs(download_configs):
     argvalues = []
     ids = []
@@ -175,7 +187,16 @@ def make_parametrize_kwargs(download_configs):
 
 
 @pytest.mark.parametrize(
-    **make_parametrize_kwargs(itertools.chain(places365(), caltech101(), caltech256(), cifar10(), cifar100()))
+    **make_parametrize_kwargs(
+        itertools.chain(
+            places365(),
+            caltech101(),
+            caltech256(),
+            cifar10(),
+            cifar100(),
+            voc(),
+        )
+    )
 )
 def test_url_is_accessible(url, md5):
     retry(lambda: assert_url_is_accessible(url))