fix(db_api): allow file path for credentials (#221)

* fix: credentials_uri parameter error * fix: combine credentials and credentials_uri * fix: nits

Author: HemangChothani

google/cloud/spanner_dbapi/connection.py

@@ -357,10 +357,13 @@ def connect(
  instances, tables and data. If not provided, will
  attempt to determine from the environment.
 
- :type credentials: :class:`~google.auth.credentials.Credentials`
+ :type credentials: Union[:class:`~google.auth.credentials.Credentials`, str]
  :param credentials: (Optional) The authorization credentials to attach to
  requests. These credentials identify this application
- to the service. If none are specified, the client will
+ to the service. These credentials may be specified as
+ a file path indicating where to retrieve the service
+ account JSON for the credentials to connect to
+ Cloud Spanner. If none are specified, the client will
  attempt to ascertain the credentials from the
  environment.
 
@@ -384,9 +387,14 @@ def connect(
  user_agent=user_agent or DEFAULT_USER_AGENT, python_version=PY_VERSION
  )
 
- client = spanner.Client(
- project=project, credentials=credentials, client_info=client_info
- )
+ if isinstance(credentials, str):
+ client = spanner.Client.from_service_account_json(
+ credentials, project=project, client_info=client_info
+ )
+ else:
+ client = spanner.Client(
+ project=project, credentials=credentials, client_info=client_info
+ )
 
  instance = client.instance(instance_id)
  if not instance.exists():

tests/unit/spanner_dbapi/test_connect.py

@@ -139,3 +139,28 @@ def test_sessions_pool(self):
  ):
  connect("test-instance", database_id, pool=pool)
  database_mock.assert_called_once_with(database_id, pool=pool)
+
+ def test_connect_w_credential_file_path(self):
+ from google.cloud.spanner_dbapi import connect
+ from google.cloud.spanner_dbapi import Connection
+
+ PROJECT = "test-project"
+ USER_AGENT = "user-agent"
+ credentials = "dummy/file/path.json"
+
+ with mock.patch(
+ "google.cloud.spanner_v1.Client.from_service_account_json"
+ ) as client_mock:
+ connection = connect(
+ "test-instance",
+ "test-database",
+ PROJECT,
+ credentials=credentials,
+ user_agent=USER_AGENT,
+ )
+
+ self.assertIsInstance(connection, Connection)
+
+ client_mock.assert_called_once_with(
+ credentials, project=PROJECT, client_info=mock.ANY
+ )