add download tests for CIFAR (pytorch#2747)

* add download tests for CIFAR

* fix tests in case of bad request

.github/workflows/tests-schedule.yml

@@ -35,7 +35,7 @@ jobs:
         run: pip install pytest
 
       - name: Run tests
-        run: pytest --durations=20 -ra test/test_datasets_download.py
+        run: pytest -ra -v test/test_datasets_download.py
 
       - uses: JasonEtco/create-an-issue@v2.4.0
         name: Create issue if download tests failed

test/test_datasets_download.py

@@ -4,6 +4,7 @@
 import unittest.mock
 from datetime import datetime
 from os import path
+from urllib.error import HTTPError
 from urllib.parse import urlparse
 from urllib.request import urlopen, Request
 
@@ -86,25 +87,26 @@ def retry(fn, times=1, wait=5.0):
         )
 
 
-def assert_server_response_ok(response, url=None):
-    msg = f"The server returned status code {response.code}"
-    if url is not None:
-        msg += f"for the the URL {url}"
-    assert 200 <= response.code < 300, msg
+@contextlib.contextmanager
+def assert_server_response_ok():
+    try:
+        yield
+    except HTTPError as error:
+        raise AssertionError(f"The server returned {error.code}: {error.reason}.") from error
 
 
 def assert_url_is_accessible(url):
     request = Request(url, headers=dict(method="HEAD"))
-    response = urlopen(request)
-    assert_server_response_ok(response, url)
+    with assert_server_response_ok():
+        urlopen(request)
 
 
 def assert_file_downloads_correctly(url, md5):
     with get_tmp_dir() as root:
         file = path.join(root, path.basename(url))
-        with urlopen(url) as response, open(file, "wb") as fh:
-            assert_server_response_ok(response, url)
-            fh.write(response.read())
+        with assert_server_response_ok():
+            with urlopen(url) as response, open(file, "wb") as fh:
+                fh.write(response.read())
 
         assert check_integrity(file, md5=md5), "The MD5 checksums mismatch"
 
@@ -125,6 +127,16 @@ 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
+
+    return make_download_configs(urls_and_md5s, name)
+
+
 def places365():
     with log_download_attempts(patch=False) as urls_and_md5s:
         for split, small in itertools.product(("train-standard", "train-challenge", "val"), (False, True)):
@@ -137,23 +149,19 @@ def places365():
 
 
 def caltech101():
-    try:
-        with log_download_attempts() as urls_and_md5s:
-            datasets.Caltech101(".", download=True)
-    except Exception:
-        pass
-
-    return make_download_configs(urls_and_md5s, "Caltech101")
+    return collect_download_configs(lambda: datasets.Caltech101(".", download=True), "Caltech101")
 
 
 def caltech256():
-    try:
-        with log_download_attempts() as urls_and_md5s:
-            datasets.Caltech256(".", download=True)
-    except Exception:
-        pass
+    return collect_download_configs(lambda: datasets.Caltech256(".", download=True), "Caltech256")
+
+
+def cifar10():
+    return collect_download_configs(lambda: datasets.CIFAR10(".", download=True), "CIFAR10")
+
 
-    return make_download_configs(urls_and_md5s, "Caltech256")
+def cifar100():
+    return collect_download_configs(lambda: datasets.CIFAR10(".", download=True), "CIFAR100")
 
 
 def make_parametrize_kwargs(download_configs):
@@ -166,7 +174,9 @@ def make_parametrize_kwargs(download_configs):
     return dict(argnames=("url", "md5"), argvalues=argvalues, ids=ids)
 
 
-@pytest.mark.parametrize(**make_parametrize_kwargs(itertools.chain(places365(), caltech101(), caltech256())))
+@pytest.mark.parametrize(
+    **make_parametrize_kwargs(itertools.chain(places365(), caltech101(), caltech256(), cifar10(), cifar100()))
+)
 def test_url_is_accessible(url, md5):
     retry(lambda: assert_url_is_accessible(url))