Storage: assigning 'Bucket.retention_policy' to None fails in systests

[tseaver]

See the non-flaky-looking failures today:

__________ TestRetentionPolicy.test_bucket_w_retention_period ______________

 = <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 = 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()
...

        BadRequest: 400 PATCH https://www.googleapis.com/storage/v1/b/w-retention-period-1541108415593?projection=full: Retention policy must have a retention period greater than 0 and less than 100 years.

@frankyn Has something changed on the back-end about this case? These tests have been passing.

[frankyn]

This is strange, I'm researching, from a brief inspection it is as if it no longer accepts the None value in Python.

[frankyn]

I think it changed based on it no longer accepts None when a Retention policy is defined. It used to accept it. I will follow-up on such subtle changes in the backend.

As for the fix, I missed this during the review, because I have learned more!
From https://github.com/googleapis/google-cloud-python/blob/master/storage/google/cloud/storage/bucket.py#L1348-L1352
Change to:

    @retention_period.setter
    def retention_period(self, value):
        """Set the retention period for items in the bucket.
        :type value: int
        :param value:
            number of seconds to retain items after upload or release from
            event-based lock.
        :raises ValueError: if the bucket's retention policy is locked.
        """
        policy = self._properties.setdefault('retentionPolicy', {})
        if value is not None:
            policy['retentionPeriod'] = str(value)
        else:
            policy = None
        self._patch_property('retentionPolicy', policy)

[frankyn]

Internal tracking bug: 115765214

[frankyn]

Short update: turns out it was a bug in the feature that has since been fixed. The client shouldn't have depended on this route in the first place. I missed this during the review.

Thanks @tseaver for the fast fix!