chore: add TYPE_CHECKING for imports (#56)

Author: jackwotherspoon

google/cloud/alloydb/connector/client.py

@@ -12,18 +12,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import logging
-from typing import List, Optional, Tuple
+from typing import List, Optional, Tuple, TYPE_CHECKING
 
 import aiohttp
 from cryptography.hazmat.primitives import serialization
-from cryptography.hazmat.primitives.asymmetric import rsa
 
-from google.auth.credentials import Credentials
 from google.auth.transport.requests import Request
 from google.cloud.alloydb.connector.utils import _create_certificate_request
 from google.cloud.alloydb.connector.version import __version__ as version
 
+if TYPE_CHECKING:
+    from cryptography.hazmat.primitives.asymmetric import rsa
+    from google.auth.credentials import Credentials
+
 USER_AGENT: str = f"alloydb-python-connector/{version}"
 API_VERSION: str = "v1beta"
 

google/cloud/alloydb/connector/connector.py

@@ -12,20 +12,25 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import asyncio
 from functools import partial
 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 cryptography.hazmat.primitives.asymmetric import rsa
 
 from google.auth import default
-from google.auth.credentials import Credentials, with_scopes_if_required
+from google.auth.credentials import with_scopes_if_required
 from google.cloud.alloydb.connector.client import AlloyDBClient
 from google.cloud.alloydb.connector.instance import Instance
 import google.cloud.alloydb.connector.pg8000 as pg8000
 
+if TYPE_CHECKING:
+    from google.auth.credentials import Credentials
+
 
 class Connector:
     """A class to configure and create connections to Cloud SQL instances.

google/cloud/alloydb/connector/instance.py

@@ -12,14 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import asyncio
 import logging
-import ssl
-from typing import Tuple
-
-from cryptography.hazmat.primitives.asymmetric import rsa
+from typing import Tuple, TYPE_CHECKING
 
-from google.cloud.alloydb.connector.client import AlloyDBClient
 from google.cloud.alloydb.connector.exceptions import RefreshError
 from google.cloud.alloydb.connector.rate_limiter import AsyncRateLimiter
 from google.cloud.alloydb.connector.refresh import (
@@ -28,6 +26,11 @@
     RefreshResult,
 )
 
+if TYPE_CHECKING:
+    import ssl
+    from cryptography.hazmat.primitives.asymmetric import rsa
+    from google.cloud.alloydb.connector.client import AlloyDBClient
+
 logger = logging.getLogger(name=__name__)
 
 

google/cloud/alloydb/connector/refresh.py

@@ -12,18 +12,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import asyncio
 from datetime import datetime
 import logging
 import ssl
 from tempfile import TemporaryDirectory
-from typing import List, Tuple
+from typing import List, Tuple, TYPE_CHECKING
 
 from cryptography import x509
-from cryptography.hazmat.primitives.asymmetric import rsa
 
 from google.cloud.alloydb.connector.utils import _write_to_file
 
+if TYPE_CHECKING:
+    from cryptography.hazmat.primitives.asymmetric import rsa
+
 logger = logging.getLogger(name=__name__)
 
 # _refresh_buffer is the amount of time before a refresh's result expires

google/cloud/alloydb/connector/utils.py

@@ -12,13 +12,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import List, Tuple
+from __future__ import annotations
+
+from typing import List, Tuple, TYPE_CHECKING
 
 from cryptography import x509
 from cryptography.hazmat.primitives import hashes, serialization
-from cryptography.hazmat.primitives.asymmetric import rsa
 from cryptography.x509.oid import NameOID
 
+if TYPE_CHECKING:
+    from cryptography.hazmat.primitives.asymmetric import rsa
+
 
 def _write_to_file(
     dir_path: str, cert_chain: List[str], client_cert: str, key: rsa.RSAPrivateKey