chore: blacken (#375)

diff --git a/tests/oauth2/test_credentials.py b/tests/oauth2/test_credentials.py
index 3231509..8bfdd7e 100644
--- a/tests/oauth2/test_credentials.py
+++ b/tests/oauth2/test_credentials.py
@@ -25,26 +25,29 @@
 from google.oauth2 import credentials
 
 
-DATA_DIR = os.path.join(os.path.dirname(__file__), '..', 'data')
+DATA_DIR = os.path.join(os.path.dirname(__file__), "..", "data")
 
-AUTH_USER_JSON_FILE = os.path.join(DATA_DIR, 'authorized_user.json')
+AUTH_USER_JSON_FILE = os.path.join(DATA_DIR, "authorized_user.json")
 
-with open(AUTH_USER_JSON_FILE, 'r') as fh:
+with open(AUTH_USER_JSON_FILE, "r") as fh:
     AUTH_USER_INFO = json.load(fh)
 
 
 class TestCredentials(object):
-    TOKEN_URI = 'https://example.com/oauth2/token'
-    REFRESH_TOKEN = 'refresh_token'
-    CLIENT_ID = 'client_id'
-    CLIENT_SECRET = 'client_secret'
+    TOKEN_URI = "https://example.com/oauth2/token"
+    REFRESH_TOKEN = "refresh_token"
+    CLIENT_ID = "client_id"
+    CLIENT_SECRET = "client_secret"
 
     @classmethod
     def make_credentials(cls):
         return credentials.Credentials(
-            token=None, refresh_token=cls.REFRESH_TOKEN,
-            token_uri=cls.TOKEN_URI, client_id=cls.CLIENT_ID,
-            client_secret=cls.CLIENT_SECRET)
+            token=None,
+            refresh_token=cls.REFRESH_TOKEN,
+            token_uri=cls.TOKEN_URI,
+            client_id=cls.CLIENT_ID,
+            client_secret=cls.CLIENT_SECRET,
+        )
 
     def test_default_state(self):
         credentials = self.make_credentials()
@@ -59,14 +62,15 @@
         assert credentials.client_id == self.CLIENT_ID
         assert credentials.client_secret == self.CLIENT_SECRET
 
-    @mock.patch('google.oauth2._client.refresh_grant', autospec=True)
+    @mock.patch("google.oauth2._client.refresh_grant", autospec=True)
     @mock.patch(
-        'google.auth._helpers.utcnow',
-        return_value=datetime.datetime.min + _helpers.CLOCK_SKEW)
+        "google.auth._helpers.utcnow",
+        return_value=datetime.datetime.min + _helpers.CLOCK_SKEW,
+    )
     def test_refresh_success(self, unused_utcnow, refresh_grant):
-        token = 'token'
+        token = "token"
         expiry = _helpers.utcnow() + datetime.timedelta(seconds=500)
-        grant_response = {'id_token': mock.sentinel.id_token}
+        grant_response = {"id_token": mock.sentinel.id_token}
         refresh_grant.return_value = (
             # Access token
             token,
@@ -75,7 +79,8 @@
             # Expiry,
             expiry,
             # Extra data
-            grant_response)
+            grant_response,
+        )
 
         request = mock.create_autospec(transport.Request)
         credentials = self.make_credentials()
@@ -85,8 +90,13 @@
 
         # Check jwt grant call.
         refresh_grant.assert_called_with(
-            request, self.TOKEN_URI, self.REFRESH_TOKEN, self.CLIENT_ID,
-            self.CLIENT_SECRET, None)
+            request,
+            self.TOKEN_URI,
+            self.REFRESH_TOKEN,
+            self.CLIENT_ID,
+            self.CLIENT_SECRET,
+            None,
+        )
 
         # Check that the credentials have the token and expiry
         assert credentials.token == token
@@ -99,24 +109,25 @@
 
     def test_refresh_no_refresh_token(self):
         request = mock.create_autospec(transport.Request)
-        credentials_ = credentials.Credentials(
-            token=None, refresh_token=None)
+        credentials_ = credentials.Credentials(token=None, refresh_token=None)
 
-        with pytest.raises(exceptions.RefreshError, match='necessary fields'):
+        with pytest.raises(exceptions.RefreshError, match="necessary fields"):
             credentials_.refresh(request)
 
         request.assert_not_called()
 
-    @mock.patch('google.oauth2._client.refresh_grant', autospec=True)
+    @mock.patch("google.oauth2._client.refresh_grant", autospec=True)
     @mock.patch(
-        'google.auth._helpers.utcnow',
-        return_value=datetime.datetime.min + _helpers.CLOCK_SKEW)
+        "google.auth._helpers.utcnow",
+        return_value=datetime.datetime.min + _helpers.CLOCK_SKEW,
+    )
     def test_credentials_with_scopes_requested_refresh_success(
-            self, unused_utcnow, refresh_grant):
-        scopes = ['email', 'profile']
-        token = 'token'
+        self, unused_utcnow, refresh_grant
+    ):
+        scopes = ["email", "profile"]
+        token = "token"
         expiry = _helpers.utcnow() + datetime.timedelta(seconds=500)
-        grant_response = {'id_token': mock.sentinel.id_token}
+        grant_response = {"id_token": mock.sentinel.id_token}
         refresh_grant.return_value = (
             # Access token
             token,
@@ -125,21 +136,31 @@
             # Expiry,
             expiry,
             # Extra data
-            grant_response)
+            grant_response,
+        )
 
         request = mock.create_autospec(transport.Request)
         creds = credentials.Credentials(
-            token=None, refresh_token=self.REFRESH_TOKEN,
-            token_uri=self.TOKEN_URI, client_id=self.CLIENT_ID,
-            client_secret=self.CLIENT_SECRET, scopes=scopes)
+            token=None,
+            refresh_token=self.REFRESH_TOKEN,
+            token_uri=self.TOKEN_URI,
+            client_id=self.CLIENT_ID,
+            client_secret=self.CLIENT_SECRET,
+            scopes=scopes,
+        )
 
         # Refresh credentials
         creds.refresh(request)
 
         # Check jwt grant call.
         refresh_grant.assert_called_with(
-            request, self.TOKEN_URI, self.REFRESH_TOKEN, self.CLIENT_ID,
-            self.CLIENT_SECRET, scopes)
+            request,
+            self.TOKEN_URI,
+            self.REFRESH_TOKEN,
+            self.CLIENT_ID,
+            self.CLIENT_SECRET,
+            scopes,
+        )
 
         # Check that the credentials have the token and expiry
         assert creds.token == token
@@ -151,17 +172,21 @@
         # expired.)
         assert creds.valid
 
-    @mock.patch('google.oauth2._client.refresh_grant', autospec=True)
+    @mock.patch("google.oauth2._client.refresh_grant", autospec=True)
     @mock.patch(
-        'google.auth._helpers.utcnow',
-        return_value=datetime.datetime.min + _helpers.CLOCK_SKEW)
+        "google.auth._helpers.utcnow",
+        return_value=datetime.datetime.min + _helpers.CLOCK_SKEW,
+    )
     def test_credentials_with_scopes_returned_refresh_success(
-            self, unused_utcnow, refresh_grant):
-        scopes = ['email', 'profile']
-        token = 'token'
+        self, unused_utcnow, refresh_grant
+    ):
+        scopes = ["email", "profile"]
+        token = "token"
         expiry = _helpers.utcnow() + datetime.timedelta(seconds=500)
-        grant_response = {'id_token': mock.sentinel.id_token,
-                          'scopes': ' '.join(scopes)}
+        grant_response = {
+            "id_token": mock.sentinel.id_token,
+            "scopes": " ".join(scopes),
+        }
         refresh_grant.return_value = (
             # Access token
             token,
@@ -170,21 +195,31 @@
             # Expiry,
             expiry,
             # Extra data
-            grant_response)
+            grant_response,
+        )
 
         request = mock.create_autospec(transport.Request)
         creds = credentials.Credentials(
-            token=None, refresh_token=self.REFRESH_TOKEN,
-            token_uri=self.TOKEN_URI, client_id=self.CLIENT_ID,
-            client_secret=self.CLIENT_SECRET, scopes=scopes)
+            token=None,
+            refresh_token=self.REFRESH_TOKEN,
+            token_uri=self.TOKEN_URI,
+            client_id=self.CLIENT_ID,
+            client_secret=self.CLIENT_SECRET,
+            scopes=scopes,
+        )
 
         # Refresh credentials
         creds.refresh(request)
 
         # Check jwt grant call.
         refresh_grant.assert_called_with(
-            request, self.TOKEN_URI, self.REFRESH_TOKEN, self.CLIENT_ID,
-            self.CLIENT_SECRET, scopes)
+            request,
+            self.TOKEN_URI,
+            self.REFRESH_TOKEN,
+            self.CLIENT_ID,
+            self.CLIENT_SECRET,
+            scopes,
+        )
 
         # Check that the credentials have the token and expiry
         assert creds.token == token
@@ -196,18 +231,22 @@
         # expired.)
         assert creds.valid
 
-    @mock.patch('google.oauth2._client.refresh_grant', autospec=True)
+    @mock.patch("google.oauth2._client.refresh_grant", autospec=True)
     @mock.patch(
-        'google.auth._helpers.utcnow',
-        return_value=datetime.datetime.min + _helpers.CLOCK_SKEW)
+        "google.auth._helpers.utcnow",
+        return_value=datetime.datetime.min + _helpers.CLOCK_SKEW,
+    )
     def test_credentials_with_scopes_refresh_failure_raises_refresh_error(
-            self, unused_utcnow, refresh_grant):
-        scopes = ['email', 'profile']
-        scopes_returned = ['email']
-        token = 'token'
+        self, unused_utcnow, refresh_grant
+    ):
+        scopes = ["email", "profile"]
+        scopes_returned = ["email"]
+        token = "token"
         expiry = _helpers.utcnow() + datetime.timedelta(seconds=500)
-        grant_response = {'id_token': mock.sentinel.id_token,
-                          'scopes': ' '.join(scopes_returned)}
+        grant_response = {
+            "id_token": mock.sentinel.id_token,
+            "scopes": " ".join(scopes_returned),
+        }
         refresh_grant.return_value = (
             # Access token
             token,
@@ -216,23 +255,34 @@
             # Expiry,
             expiry,
             # Extra data
-            grant_response)
+            grant_response,
+        )
 
         request = mock.create_autospec(transport.Request)
         creds = credentials.Credentials(
-            token=None, refresh_token=self.REFRESH_TOKEN,
-            token_uri=self.TOKEN_URI, client_id=self.CLIENT_ID,
-            client_secret=self.CLIENT_SECRET, scopes=scopes)
+            token=None,
+            refresh_token=self.REFRESH_TOKEN,
+            token_uri=self.TOKEN_URI,
+            client_id=self.CLIENT_ID,
+            client_secret=self.CLIENT_SECRET,
+            scopes=scopes,
+        )
 
         # Refresh credentials
-        with pytest.raises(exceptions.RefreshError,
-                           match='Not all requested scopes were granted'):
+        with pytest.raises(
+            exceptions.RefreshError, match="Not all requested scopes were granted"
+        ):
             creds.refresh(request)
 
         # Check jwt grant call.
         refresh_grant.assert_called_with(
-            request, self.TOKEN_URI, self.REFRESH_TOKEN, self.CLIENT_ID,
-            self.CLIENT_SECRET, scopes)
+            request,
+            self.TOKEN_URI,
+            self.REFRESH_TOKEN,
+            self.CLIENT_ID,
+            self.CLIENT_SECRET,
+            scopes,
+        )
 
         # Check that the credentials have the token and expiry
         assert creds.token == token
@@ -248,37 +298,36 @@
         info = AUTH_USER_INFO.copy()
 
         creds = credentials.Credentials.from_authorized_user_info(info)
-        assert creds.client_secret == info['client_secret']
-        assert creds.client_id == info['client_id']
-        assert creds.refresh_token == info['refresh_token']
+        assert creds.client_secret == info["client_secret"]
+        assert creds.client_id == info["client_id"]
+        assert creds.refresh_token == info["refresh_token"]
         assert creds.token_uri == credentials._GOOGLE_OAUTH2_TOKEN_ENDPOINT
         assert creds.scopes is None
 
-        scopes = ['email', 'profile']
-        creds = credentials.Credentials.from_authorized_user_info(
-            info, scopes)
-        assert creds.client_secret == info['client_secret']
-        assert creds.client_id == info['client_id']
-        assert creds.refresh_token == info['refresh_token']
+        scopes = ["email", "profile"]
+        creds = credentials.Credentials.from_authorized_user_info(info, scopes)
+        assert creds.client_secret == info["client_secret"]
+        assert creds.client_id == info["client_id"]
+        assert creds.refresh_token == info["refresh_token"]
         assert creds.token_uri == credentials._GOOGLE_OAUTH2_TOKEN_ENDPOINT
         assert creds.scopes == scopes
 
     def test_from_authorized_user_file(self):
         info = AUTH_USER_INFO.copy()
 
-        creds = credentials.Credentials.from_authorized_user_file(
-            AUTH_USER_JSON_FILE)
-        assert creds.client_secret == info['client_secret']
-        assert creds.client_id == info['client_id']
-        assert creds.refresh_token == info['refresh_token']
+        creds = credentials.Credentials.from_authorized_user_file(AUTH_USER_JSON_FILE)
+        assert creds.client_secret == info["client_secret"]
+        assert creds.client_id == info["client_id"]
+        assert creds.refresh_token == info["refresh_token"]
         assert creds.token_uri == credentials._GOOGLE_OAUTH2_TOKEN_ENDPOINT
         assert creds.scopes is None
 
-        scopes = ['email', 'profile']
+        scopes = ["email", "profile"]
         creds = credentials.Credentials.from_authorized_user_file(
-            AUTH_USER_JSON_FILE, scopes)
-        assert creds.client_secret == info['client_secret']
-        assert creds.client_id == info['client_id']
-        assert creds.refresh_token == info['refresh_token']
+            AUTH_USER_JSON_FILE, scopes
+        )
+        assert creds.client_secret == info["client_secret"]
+        assert creds.client_id == info["client_id"]
+        assert creds.refresh_token == info["refresh_token"]
         assert creds.token_uri == credentials._GOOGLE_OAUTH2_TOKEN_ENDPOINT
         assert creds.scopes == scopes