______________ TestRetentionPolicy.test_bucket_w_retention_period ______________
self = <tests.system.TestRetentionPolicy testMethod=test_bucket_w_retention_period>
    def test_bucket_w_retention_period(self):
        import datetime
        from google.api_core import exceptions
        period_secs = 10
        new_bucket_name = "w-retention-period" + unique_resource_id("-")
        bucket = retry_429(Config.CLIENT.create_bucket)(new_bucket_name)
        self.case_buckets_to_delete.append(new_bucket_name)
        bucket.retention_period = period_secs
        bucket.default_event_based_hold = False
        bucket.patch()
        self.assertEqual(bucket.retention_period, period_secs)
        self.assertIsInstance(bucket.retention_policy_effective_time, datetime.datetime)
        self.assertFalse(bucket.default_event_based_hold)
        self.assertFalse(bucket.retention_policy_locked)
        blob_name = "test-blob"
        payload = b"DEADBEEF"
        blob = bucket.blob(blob_name)
        blob.upload_from_string(payload)
        other = bucket.get_blob(blob_name)
        self.assertFalse(other.event_based_hold)
        self.assertFalse(other.temporary_hold)
        self.assertIsInstance(other.retention_expiration_time, datetime.datetime)
        with self.assertRaises(exceptions.Forbidden):
            other.delete()
        bucket.retention_period = None
        bucket.patch()
        self.assertIsNone(bucket.retention_period)
        self.assertIsNone(bucket.retention_policy_effective_time)
        self.assertFalse(bucket.default_event_based_hold)
        self.assertFalse(bucket.retention_policy_locked)
        other.reload()
        self.assertFalse(other.event_based_hold)
        self.assertFalse(other.temporary_hold)
>       self.assertIsNone(other.retention_expiration_time)
E       AssertionError: datetime.datetime(2019, 5, 6, 19, 57, 0, 946000, tzinfo=<UTC>) is not None
tests/system.py:1506: AssertionError
1 failed, 54 passed, 11 skipped, 1 error in 146.87 seconds
Command py.test --quiet tests/system.py failed with exit code 1
Session system-2.7 failed.