'A contextmanager that returns an isolated xml modulestore
Args:
contentstore: The contentstore that this modulestore should use to store
all of its assets.'

@contextmanager
def build_with_contentstore(self, contentstore=None, course_ids=None, **kwargs):

    modulestore = XMLModuleStore(DATA_DIR, course_ids=course_ids, default_class='xmodule.hidden_module.HiddenDescriptor', xblock_mixins=XBLOCK_MIXINS)
    (yield modulestore)
