CreateControllerRevision(parent metav1.Object, revision *apps.ControllerRevision, collisionCount *int32) (*apps.ControllerRevision, error)
	// DeleteControllerRevision attempts to delete revision. If the returned error is not nil, deletion has failed.
	DeleteControllerRevision(revision *apps.ControllerRevision) error
	// UpdateControllerRevision updates revision such that its Revision is equal to newRevision. Implementations

			_, err := history.CreateControllerRevision(test.existing[i].parent, test.existing[i].revision, &collisionCount)
			if err != nil {
				t.Fatal(err)
			}
		}
		err := history.DeleteControllerRevision(test.revision)
		if !test.err && err != nil {
			t.Errorf("%s: %s", test.name, err)
		}
		if test.err && err == nil {
			t.Errorf("%s: expected error", test.name)
		}
	}

		return nil
	}
	// delete any non-live history to maintain the revision limit.
	history = history[:(historyLen - historyLimit)]
	for i := 0; i < len(history); i++ {
		if err := ssc.controllerHistory.DeleteControllerRevision(history[i]); err != nil {
			return err
		}
	}
	return nil
}

// getStatefulSetRevisions returns the current and update ControllerRevisions for set. It also