Fix bigquery retry

luigi/contrib/bigquery.py

@@ -51,7 +51,7 @@ def is_error_5xx(err):
                  wait=wait_exponential(multiplier=1, min=1, max=10),
                  stop=stop_after_attempt(3),
                  reraise=True,
-                 after=lambda x: x.args[0].__initialise_client()
+                 after=lambda x: x.args[0]._initialise_client()
                  )
 
 
@@ -152,9 +152,9 @@ def __init__(self, oauth_credentials=None, descriptor='', http_=None):
         self.descriptor = descriptor
         self.http_ = http_
 
-        self.__initialise_client()
+        self._initialise_client()
 
-    def __initialise_client(self):
+    def _initialise_client(self):
         authenticate_kwargs = gcp.get_authenticate_kwargs(self.oauth_credentials, self.http_)
 
         if self.descriptor:

test/contrib/bigquery_client_test.py

@@ -0,0 +1,54 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright 2019 Spotify AB
+#
+# 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.
+#
+
+"""
+These are the unit tests for the BigQueryClient class.
+"""
+
+import unittest
+
+from mock.mock import MagicMock
+
+from luigi.contrib import bigquery
+try:
+    from googleapiclient import errors
+except ImportError:
+    raise unittest.SkipTest('Unable to load googleapiclient module')
+
+
+class BigQueryClientTest(unittest.TestCase):
+
+    def test_retry_succeeds_on_second_attempt(self):
+        client = MagicMock(spec=bigquery.BigQueryClient)
+        attempts = 0
+
+        @bigquery.bq_retry
+        def fail_once(bq_client):
+            nonlocal attempts
+            attempts += 1
+            if attempts == 1:
+                raise errors.HttpError(
+                    resp=MagicMock(status=500),
+                    content=b'{"error": {"message": "stub"}',
+                )
+            else:
+                return MagicMock(status=200)
+
+        response = fail_once(client)
+        client._initialise_client.assert_called_once()
+        self.assertEqual(attempts, 2)
+        self.assertEqual(response.status, 200)