def test_unpublished_collections_can_accept_commit_message(self):

        collection_services.update_collection(
            self.owner_id, self.COLLECTION_ID, _get_node_change_list(
                self.EXP_ID,
                collection_domain.COLLECTION_NODE_PROPERTY_ACQUIRED_SKILLS,
                ['Skill']), 'A message')

        collection_services.update_collection(
            self.owner_id, self.COLLECTION_ID, _get_node_change_list(
                self.EXP_ID,
                collection_domain.COLLECTION_NODE_PROPERTY_ACQUIRED_SKILLS,
                ['Skill']), '')

        collection_services.update_collection(
            self.owner_id, self.COLLECTION_ID, _get_node_change_list(
                self.EXP_ID,
                collection_domain.COLLECTION_NODE_PROPERTY_ACQUIRED_SKILLS,
                ['Skill']), None)
Test unpublished collections can accept optional commit messages.
dataset/ETHPy150Open oppia/oppia/core/domain/collection_services_test.py/CommitMessageHandlingTests.test_unpublished_collections_can_accept_commit_message