fix(api-core): make RetryError picklable

packages/google-api-core/google/api_core/exceptions.py

@@ -93,6 +93,9 @@ def cause(self):
     def __str__(self):
         return "{}, last exception: {}".format(self.message, self.cause)
 
+    def __reduce__(self):
+        return (type(self), (self.message, self.cause), self.__dict__)
+
 
 class _GoogleAPICallErrorMeta(type):
     """Metaclass for registering GoogleAPICallError subclasses."""

packages/google-api-core/tests/unit/test_exceptions.py

@@ -12,8 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import copy
 import http.client
 import json
+import pickle
 from unittest import mock
 
 import pytest
@@ -434,3 +436,42 @@ def test_from_grpc_error_misleading_404():
     assert exception.grpc_status_code == grpc.StatusCode.UNIMPLEMENTED
     assert "Received http2 header with status: 404" in exception.message
     assert "api_endpoint" in exception.message
+
+
+@pytest.mark.parametrize(
+    "operation",
+    [
+        lambda err: pickle.loads(pickle.dumps(err)),
+        copy.copy,
+        copy.deepcopy,
+    ],
+    ids=["pickle", "copy", "deepcopy"],
+)
+@pytest.mark.parametrize(
+    "cause",
+    [
+        exceptions.ServiceUnavailable("503 backend unavailable"),
+        None,
+    ],
+    ids=["with_cause", "none_cause"],
+)
+def test_retry_error_copy_and_pickle(operation, cause):
+    original = exceptions.RetryError("Request timed out", cause)
+    original.custom_attr = "test_value"
+
+    result = operation(original)
+
+    assert isinstance(result, exceptions.RetryError)
+    assert result.message == original.message
+    assert str(result) == str(original)
+    assert result.custom_attr == "test_value"
+
+    if cause is None:
+        assert result.cause is None
+    else:
+        if operation is copy.copy:
+            assert result.cause is original.cause
+
+        assert isinstance(result.cause, type(original.cause))
+        assert result.cause.message == original.cause.message
+        assert str(result.cause) == str(original.cause)