fix: remove enable_iam_auth from downstream kwargs and catch error (#273)

Author: jackwotherspoon

google/cloud/sql/connector/connector.py

@@ -108,11 +108,18 @@ def connect(
         # Use the InstanceConnectionManager to establish an SSL Connection.
         #
         # Return a DBAPI connection
-
+        enable_iam_auth = kwargs.pop("enable_iam_auth", self._enable_iam_auth)
         if instance_connection_string in self._instances:
             icm = self._instances[instance_connection_string]
+            if enable_iam_auth != icm._enable_iam_auth:
+                raise ValueError(
+                    "connect() called with `enable_iam_auth={}`, but previously used "
+                    "enable_iam_auth={}`. If you require both for your use case, "
+                    "please use a new connector.Connector object.".format(
+                        enable_iam_auth, icm._enable_iam_auth
+                    )
+                )
         else:
-            enable_iam_auth = kwargs.pop("enable_iam_auth", self._enable_iam_auth)
             icm = InstanceConnectionManager(
                 instance_connection_string,
                 driver,

tests/unit/test_connector.py

@@ -27,6 +27,25 @@
 from typing import Any
 
 
+class MockInstanceConnectionManager:
+    _enable_iam_auth: bool
+
+    def __init__(
+        self,
+        enable_iam_auth: bool = False,
+    ) -> None:
+        self._enable_iam_auth = enable_iam_auth
+
+    def connect(
+        self,
+        driver: str,
+        ip_type: IPTypes,
+        timeout: int,
+        **kwargs: Any,
+    ) -> Any:
+        return True
+
+
 def test_connect_timeout(
     fake_credentials: Credentials, async_loop: asyncio.AbstractEventLoop
 ) -> None:
@@ -59,6 +78,31 @@ async def timeout_stub(*args: Any, **kwargs: Any) -> None:
         )
 
 
+def test_connect_enable_iam_auth_error() -> None:
+    """Test that calling connect() with different enable_iam_auth
+    argument values throws error."""
+    connect_string = "my-project:my-region:my-instance"
+    default_connector = connector.Connector()
+    with patch(
+        "google.cloud.sql.connector.connector.InstanceConnectionManager"
+    ) as mock_icm:
+        mock_icm.return_value = MockInstanceConnectionManager(enable_iam_auth=False)
+        conn = default_connector.connect(
+            connect_string,
+            "pg8000",
+            enable_iam_auth=False,
+        )
+        assert conn is True
+        # try to connect using enable_iam_auth=True, should raise error
+        pytest.raises(
+            ValueError,
+            default_connector.connect,
+            connect_string,
+            "pg8000",
+            enable_iam_auth=True,
+        )
+
+
 def test_default_Connector_Init() -> None:
     """Test that default Connector __init__ sets properties properly."""
     default_connector = connector.Connector()