chore: import upstream snapshot with attribution

tests/unittests/integrations/gcs/test_client.py

@@ -0,0 +1,56 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from unittest import mock
+
+from google.adk.integrations.gcs import client
+from google.auth.credentials import Credentials
+from google.cloud import storage
+
+
+def test_get_gcs_client():
+  """Test get_gcs_client function."""
+  with mock.patch.object(storage, "Client", autospec=True) as MockGCSClient:
+    mock_creds = mock.create_autospec(Credentials, instance=True)
+    client.get_gcs_client(project="test-project", credentials=mock_creds)
+    MockGCSClient.assert_called_once_with(
+        project="test-project",
+        credentials=mock_creds,
+        client_info=mock.ANY,
+    )
+
+
+def test_get_gcs_client_cache():
+  """Test get_gcs_client caches and reuses the client instance."""
+  client._client_cache.clear()  # pylint: disable=protected-access
+
+  with mock.patch.object(storage, "Client", autospec=True) as MockGCSClient:
+    mock_creds = mock.create_autospec(Credentials, instance=True)
+
+    # First call - cache miss
+    client1 = client.get_gcs_client(
+        project="test-project", credentials=mock_creds
+    )
+
+    # Second call - cache hit
+    client2 = client.get_gcs_client(
+        project="test-project", credentials=mock_creds
+    )
+
+    assert client1 is client2
+    MockGCSClient.assert_called_once_with(
+        project="test-project",
+        credentials=mock_creds,
+        client_info=mock.ANY,
+    )