chore: add TYPE_CHECKING for imports (#756)

Author: jackwotherspoon

google/cloud/sql/connector/connector.py

@@ -13,14 +13,15 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 """
+from __future__ import annotations
+
 import asyncio
 from functools import partial
 import logging
 from threading import Thread
 from types import TracebackType
-from typing import Any, Dict, Optional, Type
+from typing import Any, Dict, Optional, Type, TYPE_CHECKING
 
-from google.auth.credentials import Credentials
 import google.cloud.sql.connector.asyncpg as asyncpg
 from google.cloud.sql.connector.exceptions import ConnectorLoopError
 from google.cloud.sql.connector.instance import (
@@ -32,6 +33,9 @@
 import google.cloud.sql.connector.pytds as pytds
 from google.cloud.sql.connector.utils import format_database_user, generate_keys
 
+if TYPE_CHECKING:
+    from google.auth.credentials import Credentials
+
 logger = logging.getLogger(name=__name__)
 
 ASYNC_DRIVERS = ["asyncpg"]

google/cloud/sql/connector/instance.py

@@ -13,8 +13,9 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 """
+from __future__ import annotations
+
 import asyncio
-import datetime
 from enum import Enum
 import logging
 import ssl
@@ -24,6 +25,7 @@
     Dict,
     Optional,
     Tuple,
+    TYPE_CHECKING,
 )
 
 import aiohttp
@@ -47,6 +49,9 @@
 from google.cloud.sql.connector.utils import _auth_init, write_to_file
 from google.cloud.sql.connector.version import __version__ as version
 
+if TYPE_CHECKING:
+    import datetime
+
 logger = logging.getLogger(name=__name__)
 
 APPLICATION_NAME = "cloud-sql-python-connector"

google/cloud/sql/connector/refresh_utils.py

@@ -13,18 +13,20 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 """
+from __future__ import annotations
+
 import asyncio
 import copy
 import datetime
 import logging
-from typing import Any, Dict, List
-
-import aiohttp
+from typing import Any, Dict, List, TYPE_CHECKING
 
-import google.auth
 from google.auth.credentials import Credentials, Scoped
 import google.auth.transport.requests
 
+if TYPE_CHECKING:
+    import aiohttp
+
 logger = logging.getLogger(name=__name__)
 
 _sql_api_version: str = "v1beta4"