chore: blacken (#375)

diff --git a/tests/oauth2/test__client.py b/tests/oauth2/test__client.py
index 6fc4c3b..c415a1f 100644
--- a/tests/oauth2/test__client.py
+++ b/tests/oauth2/test__client.py
@@ -30,42 +30,44 @@
 from google.oauth2 import _client
 
 
-DATA_DIR = os.path.join(os.path.dirname(__file__), '..', 'data')
+DATA_DIR = os.path.join(os.path.dirname(__file__), "..", "data")
 
-with open(os.path.join(DATA_DIR, 'privatekey.pem'), 'rb') as fh:
+with open(os.path.join(DATA_DIR, "privatekey.pem"), "rb") as fh:
     PRIVATE_KEY_BYTES = fh.read()
 
-SIGNER = crypt.RSASigner.from_string(PRIVATE_KEY_BYTES, '1')
+SIGNER = crypt.RSASigner.from_string(PRIVATE_KEY_BYTES, "1")
 
-SCOPES_AS_LIST = ['https://www.googleapis.com/auth/pubsub',
-                  'https://www.googleapis.com/auth/logging.write']
-SCOPES_AS_STRING = ('https://www.googleapis.com/auth/pubsub'
-                    ' https://www.googleapis.com/auth/logging.write')
+SCOPES_AS_LIST = [
+    "https://www.googleapis.com/auth/pubsub",
+    "https://www.googleapis.com/auth/logging.write",
+]
+SCOPES_AS_STRING = (
+    "https://www.googleapis.com/auth/pubsub"
+    " https://www.googleapis.com/auth/logging.write"
+)
 
 
 def test__handle_error_response():
-    response_data = json.dumps({
-        'error': 'help',
-        'error_description': 'I\'m alive'})
+    response_data = json.dumps({"error": "help", "error_description": "I'm alive"})
 
     with pytest.raises(exceptions.RefreshError) as excinfo:
         _client._handle_error_response(response_data)
 
-    assert excinfo.match(r'help: I\'m alive')
+    assert excinfo.match(r"help: I\'m alive")
 
 
 def test__handle_error_response_non_json():
-    response_data = 'Help, I\'m alive'
+    response_data = "Help, I'm alive"
 
     with pytest.raises(exceptions.RefreshError) as excinfo:
         _client._handle_error_response(response_data)
 
-    assert excinfo.match(r'Help, I\'m alive')
+    assert excinfo.match(r"Help, I\'m alive")
 
 
-@mock.patch('google.auth._helpers.utcnow', return_value=datetime.datetime.min)
+@mock.patch("google.auth._helpers.utcnow", return_value=datetime.datetime.min)
 def test__parse_expiry(unused_utcnow):
-    result = _client._parse_expiry({'expires_in': 500})
+    result = _client._parse_expiry({"expires_in": 500})
     assert result == datetime.datetime.min + datetime.timedelta(seconds=500)
 
 
@@ -76,188 +78,214 @@
 def make_request(response_data, status=http_client.OK):
     response = mock.create_autospec(transport.Response, instance=True)
     response.status = status
-    response.data = json.dumps(response_data).encode('utf-8')
+    response.data = json.dumps(response_data).encode("utf-8")
     request = mock.create_autospec(transport.Request)
     request.return_value = response
     return request
 
 
 def test__token_endpoint_request():
-    request = make_request({'test': 'response'})
+    request = make_request({"test": "response"})
 
     result = _client._token_endpoint_request(
-        request, 'http://example.com', {'test': 'params'})
+        request, "http://example.com", {"test": "params"}
+    )
 
     # Check request call
     request.assert_called_with(
-        method='POST',
-        url='http://example.com',
-        headers={'content-type': 'application/x-www-form-urlencoded'},
-        body='test=params')
+        method="POST",
+        url="http://example.com",
+        headers={"content-type": "application/x-www-form-urlencoded"},
+        body="test=params",
+    )
 
     # Check result
-    assert result == {'test': 'response'}
+    assert result == {"test": "response"}
 
 
 def test__token_endpoint_request_error():
     request = make_request({}, status=http_client.BAD_REQUEST)
 
     with pytest.raises(exceptions.RefreshError):
-        _client._token_endpoint_request(request, 'http://example.com', {})
+        _client._token_endpoint_request(request, "http://example.com", {})
 
 
 def test__token_endpoint_request_internal_failure_error():
-    request = make_request({'error': 'internal_failure',
-                            'error_description': 'internal_failure'},
-                           status=http_client.BAD_REQUEST)
+    request = make_request(
+        {"error": "internal_failure", "error_description": "internal_failure"},
+        status=http_client.BAD_REQUEST,
+    )
 
     with pytest.raises(exceptions.RefreshError):
         _client._token_endpoint_request(
-            request, 'http://example.com',
-            {'error': 'internal_failure',
-             'error_description': 'internal_failure'})
+            request,
+            "http://example.com",
+            {"error": "internal_failure", "error_description": "internal_failure"},
+        )
 
 
 def verify_request_params(request, params):
-    request_body = request.call_args[1]['body']
+    request_body = request.call_args[1]["body"]
     request_params = urllib.parse.parse_qs(request_body)
 
     for key, value in six.iteritems(params):
         assert request_params[key][0] == value
 
 
-@mock.patch('google.auth._helpers.utcnow', return_value=datetime.datetime.min)
+@mock.patch("google.auth._helpers.utcnow", return_value=datetime.datetime.min)
 def test_jwt_grant(utcnow):
-    request = make_request({
-        'access_token': 'token',
-        'expires_in': 500,
-        'extra': 'data'})
+    request = make_request(
+        {"access_token": "token", "expires_in": 500, "extra": "data"}
+    )
 
     token, expiry, extra_data = _client.jwt_grant(
-        request, 'http://example.com', 'assertion_value')
+        request, "http://example.com", "assertion_value"
+    )
 
     # Check request call
-    verify_request_params(request, {
-        'grant_type': _client._JWT_GRANT_TYPE,
-        'assertion': 'assertion_value'
-    })
+    verify_request_params(
+        request, {"grant_type": _client._JWT_GRANT_TYPE, "assertion": "assertion_value"}
+    )
 
     # Check result
-    assert token == 'token'
+    assert token == "token"
     assert expiry == utcnow() + datetime.timedelta(seconds=500)
-    assert extra_data['extra'] == 'data'
+    assert extra_data["extra"] == "data"
 
 
 def test_jwt_grant_no_access_token():
-    request = make_request({
-        # No access token.
-        'expires_in': 500,
-        'extra': 'data'})
+    request = make_request(
+        {
+            # No access token.
+            "expires_in": 500,
+            "extra": "data",
+        }
+    )
 
     with pytest.raises(exceptions.RefreshError):
-        _client.jwt_grant(request, 'http://example.com', 'assertion_value')
+        _client.jwt_grant(request, "http://example.com", "assertion_value")
 
 
 def test_id_token_jwt_grant():
     now = _helpers.utcnow()
     id_token_expiry = _helpers.datetime_to_secs(now)
-    id_token = jwt.encode(SIGNER, {'exp': id_token_expiry}).decode('utf-8')
-    request = make_request({
-        'id_token': id_token,
-        'extra': 'data'})
+    id_token = jwt.encode(SIGNER, {"exp": id_token_expiry}).decode("utf-8")
+    request = make_request({"id_token": id_token, "extra": "data"})
 
     token, expiry, extra_data = _client.id_token_jwt_grant(
-        request, 'http://example.com', 'assertion_value')
+        request, "http://example.com", "assertion_value"
+    )
 
     # Check request call
-    verify_request_params(request, {
-        'grant_type': _client._JWT_GRANT_TYPE,
-        'assertion': 'assertion_value'
-    })
+    verify_request_params(
+        request, {"grant_type": _client._JWT_GRANT_TYPE, "assertion": "assertion_value"}
+    )
 
     # Check result
     assert token == id_token
     # JWT does not store microseconds
     now = now.replace(microsecond=0)
     assert expiry == now
-    assert extra_data['extra'] == 'data'
+    assert extra_data["extra"] == "data"
 
 
 def test_id_token_jwt_grant_no_access_token():
-    request = make_request({
-        # No access token.
-        'expires_in': 500,
-        'extra': 'data'})
+    request = make_request(
+        {
+            # No access token.
+            "expires_in": 500,
+            "extra": "data",
+        }
+    )
 
     with pytest.raises(exceptions.RefreshError):
-        _client.id_token_jwt_grant(
-            request, 'http://example.com', 'assertion_value')
+        _client.id_token_jwt_grant(request, "http://example.com", "assertion_value")
 
 
-@mock.patch('google.auth._helpers.utcnow', return_value=datetime.datetime.min)
+@mock.patch("google.auth._helpers.utcnow", return_value=datetime.datetime.min)
 def test_refresh_grant(unused_utcnow):
-    request = make_request({
-        'access_token': 'token',
-        'refresh_token': 'new_refresh_token',
-        'expires_in': 500,
-        'extra': 'data'})
+    request = make_request(
+        {
+            "access_token": "token",
+            "refresh_token": "new_refresh_token",
+            "expires_in": 500,
+            "extra": "data",
+        }
+    )
 
     token, refresh_token, expiry, extra_data = _client.refresh_grant(
-        request, 'http://example.com', 'refresh_token', 'client_id',
-        'client_secret')
+        request, "http://example.com", "refresh_token", "client_id", "client_secret"
+    )
 
     # Check request call
-    verify_request_params(request, {
-        'grant_type': _client._REFRESH_GRANT_TYPE,
-        'refresh_token': 'refresh_token',
-        'client_id': 'client_id',
-        'client_secret': 'client_secret'
-    })
+    verify_request_params(
+        request,
+        {
+            "grant_type": _client._REFRESH_GRANT_TYPE,
+            "refresh_token": "refresh_token",
+            "client_id": "client_id",
+            "client_secret": "client_secret",
+        },
+    )
 
     # Check result
-    assert token == 'token'
-    assert refresh_token == 'new_refresh_token'
+    assert token == "token"
+    assert refresh_token == "new_refresh_token"
     assert expiry == datetime.datetime.min + datetime.timedelta(seconds=500)
-    assert extra_data['extra'] == 'data'
+    assert extra_data["extra"] == "data"
 
 
-@mock.patch('google.auth._helpers.utcnow', return_value=datetime.datetime.min)
+@mock.patch("google.auth._helpers.utcnow", return_value=datetime.datetime.min)
 def test_refresh_grant_with_scopes(unused_utcnow):
-    request = make_request({
-        'access_token': 'token',
-        'refresh_token': 'new_refresh_token',
-        'expires_in': 500,
-        'extra': 'data',
-        'scope': SCOPES_AS_STRING})
+    request = make_request(
+        {
+            "access_token": "token",
+            "refresh_token": "new_refresh_token",
+            "expires_in": 500,
+            "extra": "data",
+            "scope": SCOPES_AS_STRING,
+        }
+    )
 
     token, refresh_token, expiry, extra_data = _client.refresh_grant(
-        request, 'http://example.com', 'refresh_token', 'client_id',
-        'client_secret', SCOPES_AS_LIST)
+        request,
+        "http://example.com",
+        "refresh_token",
+        "client_id",
+        "client_secret",
+        SCOPES_AS_LIST,
+    )
 
     # Check request call.
-    verify_request_params(request, {
-        'grant_type': _client._REFRESH_GRANT_TYPE,
-        'refresh_token': 'refresh_token',
-        'client_id': 'client_id',
-        'client_secret': 'client_secret',
-        'scope': SCOPES_AS_STRING
-    })
+    verify_request_params(
+        request,
+        {
+            "grant_type": _client._REFRESH_GRANT_TYPE,
+            "refresh_token": "refresh_token",
+            "client_id": "client_id",
+            "client_secret": "client_secret",
+            "scope": SCOPES_AS_STRING,
+        },
+    )
 
     # Check result.
-    assert token == 'token'
-    assert refresh_token == 'new_refresh_token'
+    assert token == "token"
+    assert refresh_token == "new_refresh_token"
     assert expiry == datetime.datetime.min + datetime.timedelta(seconds=500)
-    assert extra_data['extra'] == 'data'
+    assert extra_data["extra"] == "data"
 
 
 def test_refresh_grant_no_access_token():
-    request = make_request({
-        # No access token.
-        'refresh_token': 'new_refresh_token',
-        'expires_in': 500,
-        'extra': 'data'})
+    request = make_request(
+        {
+            # No access token.
+            "refresh_token": "new_refresh_token",
+            "expires_in": 500,
+            "extra": "data",
+        }
+    )
 
     with pytest.raises(exceptions.RefreshError):
         _client.refresh_grant(
-            request, 'http://example.com', 'refresh_token', 'client_id',
-            'client_secret')
+            request, "http://example.com", "refresh_token", "client_id", "client_secret"
+        )