diff --git a/google/cloud/alloydb/connector/enums.py b/google/cloud/alloydb/connector/enums.py
index eab5a63a..b1b2086b 100644
--- a/google/cloud/alloydb/connector/enums.py
+++ b/google/cloud/alloydb/connector/enums.py
@@ -22,9 +22,9 @@ class IPTypes(Enum):
     Enum for specifying IP type to connect to AlloyDB with.
     """
 
-    PUBLIC: str = "PUBLIC"
-    PRIVATE: str = "PRIVATE"
-    PSC: str = "PSC"
+    PUBLIC = "PUBLIC"
+    PRIVATE = "PRIVATE"
+    PSC = "PSC"
 
     @classmethod
     def _missing_(cls, value: object) -> None:
@@ -39,8 +39,8 @@ class RefreshStrategy(Enum):
     Enum for specifying refresh strategy to connect to AlloyDB with.
     """
 
-    LAZY: str = "LAZY"
-    BACKGROUND: str = "BACKGROUND"
+    LAZY = "LAZY"
+    BACKGROUND = "BACKGROUND"
 
     @classmethod
     def _missing_(cls, value: object) -> None:
diff --git a/requirements-test.txt b/requirements-test.txt
index d0c14928..605dd99b 100644
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1,6 +1,15 @@
 asyncpg==0.30.0
 mock==5.1.0
 pg8000==1.31.2
+
+# psycopg 2.9.10 isn't supported on Python 3.9 for macos-latest GitHub runner.
+# It is supported for macos-12 runner:
+# https://github.com/psycopg/psycopg2/issues/1737. But macos-12 runner is
+# deprecated: https://github.com/actions/runner-images/issues/10721. So we
+# install psycopg 2.9.9 on Python 3.9 for macos-latest runner.
+psycopg2-binary==2.9.9; python_version == "3.9" and sys_platform == "darwin" 
+psycopg2-binary==2.9.10; python_version != "3.9" or sys_platform != "darwin"
+
 pytest==8.3.4
 pytest-asyncio==0.24.0
 pytest-cov==6.0.0
diff --git a/docs/samples/test_psycopg2_direct_connection.py b/tests/system/test_psycopg2_direct_connection.py
similarity index 100%
rename from docs/samples/test_psycopg2_direct_connection.py
rename to tests/system/test_psycopg2_direct_connection.py