test: Support running the test suite without oauth2client (#2021)

* test: make MockCredentials class standalone

Remove the inheritance of MockCredentials from oauth2client.Credentials.
This is unnecessary, and removing it makes it possible to run
the respective tests without oauth2client installed.

* test: Support testing without oauth2client

Make it possible to run the test suite without oauth2client, by skipping
the few tests that specifically require it.  Given that oauth2client
is deprecated, we are aiming towards removing it entirely from Gentoo
and the unconditional imports in the test suite are a blocker for that.

* test: Test without oauth2client as well

noxfile.py

@@ -84,6 +84,7 @@ def format(session):
 @nox.parametrize(
     "oauth2client",
     [
+        None,
         "oauth2client<2dev",
         "oauth2client>=2,<=3dev",
         "oauth2client>=3,<=4dev",
@@ -96,7 +97,8 @@ def unit(session, oauth2client):
     shutil.rmtree("build", ignore_errors=True)
 
     session.install(*test_dependencies)
-    session.install(oauth2client)
+    if oauth2client is not None:
+        session.install(oauth2client)
 
     # Create and install wheels
     session.run("python3", "setup.py", "bdist_wheel")

tests/test__auth.py

@@ -18,7 +18,13 @@
 import google.auth.credentials
 import google_auth_httplib2
 import httplib2
-import oauth2client.client
+
+try:
+    import oauth2client.client
+
+    HAS_OAUTH2CLIENT = True
+except ImportError:
+    HAS_OAUTH2CLIENT = False
 
 from googleapiclient import _auth
 
@@ -105,6 +111,7 @@ def test_authorized_http(self):
         self.assertGreater(authorized_http.http.timeout, 0)
 
 
+@unittest.skipIf(not HAS_OAUTH2CLIENT, "oauth2client unavailable.")
 class TestAuthWithOAuth2Client(unittest.TestCase):
     def setUp(self):
         _auth.HAS_GOOGLE_AUTH = False

tests/test_discovery.py

@@ -43,11 +43,17 @@
 from google.auth.exceptions import MutualTLSChannelError
 import google_auth_httplib2
 import httplib2
-from oauth2client import GOOGLE_TOKEN_URI
-from oauth2client.client import GoogleCredentials, OAuth2Credentials
 from parameterized import parameterized
 import uritemplate
 
+try:
+    from oauth2client import GOOGLE_TOKEN_URI
+    from oauth2client.client import GoogleCredentials, OAuth2Credentials
+
+    HAS_OAUTH2CLIENT = True
+except ImportError:
+    HAS_OAUTH2CLIENT = False
+
 from googleapiclient import _helpers as util
 from googleapiclient.discovery import (
     DISCOVERY_URI,
@@ -1513,6 +1519,7 @@ def test_plus_resources(self):
         self.assertTrue(getattr(plus, "activities"))
         self.assertTrue(getattr(plus, "people"))
 
+    @unittest.skipIf(not HAS_OAUTH2CLIENT, "oauth2client unavailable.")
     def test_oauth2client_credentials(self):
         credentials = mock.Mock(spec=GoogleCredentials)
         credentials.create_scoped_required.return_value = False
@@ -2198,6 +2205,7 @@ def _dummy_token(self):
             user_agent,
         )
 
+    @unittest.skipIf(not HAS_OAUTH2CLIENT, "oauth2client unavailable.")
     def test_pickle_with_credentials(self):
         credentials = self._dummy_token()
         http = self._dummy_zoo_request()

tests/test_http.py

@@ -38,7 +38,6 @@
 import urllib
 
 import httplib2
-from oauth2client.client import Credentials
 
 from googleapiclient.discovery import build
 from googleapiclient.errors import BatchError, HttpError, InvalidChunkSizeError
@@ -60,7 +59,7 @@
 from googleapiclient.model import JsonModel
 
 
-class MockCredentials(Credentials):
+class MockCredentials:
     """Mock class for all Credentials objects."""
 
     def __init__(self, bearer_token, expired=False):