fix: support 'retry' for ops built from HTTP/gRPC responses

Closes #87.

google/api_core/operation.py

@@ -192,19 +192,24 @@ def cancelled(self):
         )
 
 
-def _refresh_http(api_request, operation_name):
+def _refresh_http(api_request, operation_name, retry=None):
     """Refresh an operation using a JSON/HTTP client.
 
     Args:
         api_request (Callable): A callable used to make an API request. This
             should generally be
             :meth:`google.cloud._http.Connection.api_request`.
         operation_name (str): The name of the operation.
+        retry (google.api_core.retry.Retry): (Optional) retry policy
 
     Returns:
         google.longrunning.operations_pb2.Operation: The operation.
     """
     path = "operations/{}".format(operation_name)
+
+    if retry is not None:
+        api_request = retry(api_request)
+
     api_response = api_request(method="GET", path=path)
     return json_format.ParseDict(api_response, operations_pb2.Operation())
 
@@ -249,19 +254,25 @@ def from_http_json(operation, api_request, result_type, **kwargs):
     return Operation(operation_proto, refresh, cancel, result_type, **kwargs)
 
 
-def _refresh_grpc(operations_stub, operation_name):
+def _refresh_grpc(operations_stub, operation_name, retry=None):
     """Refresh an operation using a gRPC client.
 
     Args:
         operations_stub (google.longrunning.operations_pb2.OperationsStub):
             The gRPC operations stub.
         operation_name (str): The name of the operation.
+        retry (google.api_core.retry.Retry): (Optional) retry policy
 
     Returns:
         google.longrunning.operations_pb2.Operation: The operation.
     """
     request_pb = operations_pb2.GetOperationRequest(name=operation_name)
-    return operations_stub.GetOperation(request_pb)
+
+    rpc = operations_stub.GetOperation
+    if retry is not None:
+        rpc = retry(rpc)
+
+    return rpc(request_pb)
 
 
 def _cancel_grpc(operations_stub, operation_name):

tests/unit/test_operation.py

@@ -177,17 +177,39 @@ def test_unexpected_result():
 
 
 def test__refresh_http():
-    api_request = mock.Mock(return_value={"name": TEST_OPERATION_NAME, "done": True})
+    json_response = {"name": TEST_OPERATION_NAME, "done": True}
+    api_request = mock.Mock(return_value=json_response)
 
     result = operation._refresh_http(api_request, TEST_OPERATION_NAME)
 
+    assert isinstance(result, operations_pb2.Operation)
     assert result.name == TEST_OPERATION_NAME
     assert result.done is True
+
     api_request.assert_called_once_with(
         method="GET", path="operations/{}".format(TEST_OPERATION_NAME)
     )
 
 
+def test__refresh_http_w_retry():
+    json_response = {"name": TEST_OPERATION_NAME, "done": True}
+    api_request = mock.Mock()
+    retry = mock.Mock()
+    retry.return_value.return_value = json_response
+
+    result = operation._refresh_http(api_request, TEST_OPERATION_NAME, retry=retry)
+
+    assert isinstance(result, operations_pb2.Operation)
+    assert result.name == TEST_OPERATION_NAME
+    assert result.done is True
+
+    api_request.assert_not_called()
+    retry.assert_called_once_with(api_request)
+    retry.return_value.assert_called_once_with(
+        method="GET", path="operations/{}".format(TEST_OPERATION_NAME)
+    )
+
+
 def test__cancel_http():
     api_request = mock.Mock()
 
@@ -224,6 +246,21 @@ def test__refresh_grpc():
     operations_stub.GetOperation.assert_called_once_with(expected_request)
 
 
+def test__refresh_grpc_w_retry():
+    operations_stub = mock.Mock(spec=["GetOperation"])
+    expected_result = make_operation_proto(done=True)
+    retry = mock.Mock()
+    retry.return_value.return_value = expected_result
+
+    result = operation._refresh_grpc(operations_stub, TEST_OPERATION_NAME, retry=retry)
+
+    assert result == expected_result
+    expected_request = operations_pb2.GetOperationRequest(name=TEST_OPERATION_NAME)
+    operations_stub.GetOperation.assert_not_called()
+    retry.assert_called_once_with(operations_stub.GetOperation)
+    retry.return_value.assert_called_once_with(expected_request)
+
+
 def test__cancel_grpc():
     operations_stub = mock.Mock(spec=["CancelOperation"])