Jest测试Redux Saga无法在调度时读取未定义的属性'then'

Question

我已经在堆栈溢出中看到了几个类似的条目，但是与我面临的这个问题并不完全相关。我们正在使用Jest进行测试，并使用redux-saga进行存储。

[最近，我们试图摆脱茉莉花，走向杰斯特。该测试曾经适用于Jasmine，但不适用于Jest。

这是违规测试，

  describe('componentWillReceiveProps method', () => {
    it('should call dispatch if entityType is changed', (done) => {
      const {wrapper, props} = setup();
      wrapperInstance = wrapper.instance();
      wrapperInstance.isPagePoppedFromHistory = false;

      setTimeout(() => {
        expect(props.dispatch).toHaveBeenCalled();
        done();
      }, 300);
      wrapperInstance.UNSAFE_componentWillReceiveProps(Object.assign({}, props, {
        entityType: {key: ENTITY_TYPE_HCO}
      }));
    });
  });

收到的错误是

Error: Uncaught [TypeError: Cannot read property 'then' of undefined]
        at reportException (node_modules/jsdom/lib/jsdom/living/helpers/runtime-script-errors.js:62:24)
        at Timeout.callback [as _onTimeout] (node_modules/jsdom/lib/jsdom/browser/Window.js:645:7)
        at ontimeout (timers.js:498:11)
        at tryOnTimeout (timers.js:323:5)
        at Timer.listOnTimeout (timers.js:290:5) TypeError: Cannot read property 'then' of undefined
        at UNSAFE_componentWillReceiveProps.setTimeout (/index.js:294:11)
        at Timeout.callback [as _onTimeout] (/Window.js:643:19)
        at ontimeout (timers.js:498:11)
        at tryOnTimeout (timers.js:323:5)
        at Timer.listOnTimeout (timers.js:290:5)

违反组件的代码行是这些

componentWillReceiveProps(){
 ...
 setTimeout(() => {
          dispatch(fetchTableResults(resultsLimit, filterParams, qString, currentOrderOption,
            undefined, undefined, resultBounds))
            .then(() => {
              dispatch(changePageNumber(nextPage));
            });
        });

 ...
}

关于我们为什么要看到这个的任何想法？任何帮助将不胜感激。

Answer 1

按照xdeepakv的建议结束了模拟调度方法。