Update tests/client/transports/test_grpc_client.py

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: cchinchilla-dev

tests/client/transports/test_grpc_client.py

@@ -544,17 +544,20 @@ def test_get_grpc_metadata(
     assert metadata == expected_metadata
 
 
+@pytest.mark.parametrize(
+    'test_extensions',
+    [
+        (['ext1']),  # Test with explicit extensions
+        (None),      # Test with transport's default extensions
+    ],
+)
 def test_get_grpc_metadata_uses_lowercase_header_key(
     grpc_transport: GrpcTransport,
+    test_extensions: list[str] | None,
 ) -> None:
     """Test gRPC metadata header key is always lowercase."""
     # Regression: gRPC rejects non-lowercase metadata keys
-    metadata = grpc_transport._get_grpc_metadata(['ext1'])
-    assert metadata is not None
-    key, _ = metadata[0]
-    assert key == key.lower()
-
-    metadata = grpc_transport._get_grpc_metadata()
+    metadata = grpc_transport._get_grpc_metadata(test_extensions)
     assert metadata is not None
     key, _ = metadata[0]
     assert key == key.lower()