def test_withUnsetOnReturn(self):
        action = Action(MemoryLogger(), "", TaskLevel(level=[]), "")
        with action:
            pass
        self.assertIs(currentAction(), None)
L{Action.__exit__} unsets the action on successful block finish.
dataset/ETHPy150Open ClusterHQ/eliot/eliot/tests/test_action.py/ActionTests.test_withUnsetOnReturn