为什么我的 jest async action creator 测试不起作用？

Question

我是单元测试的新手，正在尝试通过我的 react-redux 项目来编写一些测试。

为什么这个测试不起作用，我怎样才能让它通过？

这是测试。我想测试我的 fetch posts action creator。这是一个小型博客应用程序。:

import configureStore from 'redux-mock-store'; // ES6 modules
import { findSinglePost, sendEdit, changeRedirect, checkBoxChange } from '../client/redux/actions/postActions';
import thunk from 'redux-thunk';
import axios from 'axios';

const middlewares = [thunk];
const mockStore = configureStore(middlewares);
describe('asynchronous action creators', () => {

  it('should fetch posts', () => {
    let store = mockStore({})

    //my async action creator. It uses mock data that's in the same folder.
    const fetchPosts = () => function(dispatch) {
      dispatch({type: 'FETCH_POSTS'});

      return axios.get('./MOCK.json').then((response) => {
        dispatch({type: 'FETCH_POSTS_FUFILLED', payload: response.data});
      }).catch((err) => {
        dispatch({type: 'FETCH_POSTS_REJECTED', payload: err});
      });
    };
    //this doesn't equal FETCH_POSTS_FUFILLED, it ends up equaling just "FETCH_POSTS"
    return store.dispatch(fetchPosts()).then(() => {
      const actions = store.getActions();
      expect(actions[0]).toEqual({type: 'FETCH_POSTS_FUFILLED'});
    })
  })
});

这是 jest 的反馈。我希望它等于 'FETCH_POSTS_'FUFILLED'，但它返回 'FETCH_POSTS'。 :

 FAIL  _test_\actions.test.js
  ● asynchronous action creators › should fetch posts

    expect(received).toEqual(expected)

    Expected value to equal:
      {"type": "FETCH_POSTS_FUFILLED"}
    Received:
      {"type": "FETCH_POSTS"}

    Difference:

    - Expected
    + Received

      Object {
    -   "type": "FETCH_POSTS_FUFILLED",
    +   "type": "FETCH_POSTS",
      }

      88 |     return store.dispatch(fetchPosts()).then(() => {
      89 |       const actions = store.getActions();
    > 90 |       expect(actions[0]).toEqual({type: 'FETCH_POSTS_FUFILLED'});
      91 |     })
      92 |   })
      93 | });

      at _test_/actions.test.js:90:26

 PASS  client\views\LoginPage\LoginPage.test.jsx

Test Suites: 1 failed, 1 passed, 2 total
Tests:       1 failed, 5 passed, 6 total
Snapshots:   0 total
Time:        1.49s
Ran all test suites related to changed files.

还有，这里是项目的githubrepo如果你想尝试运行的话

此外，如果业界有更广为人知的标准方法来执行此操作，我会喜欢这个建议。

编辑：

当我将 actions[0] 更改为 actions[1] 时，出现此错误：

Expected value to equal:
  {"type": "FETCH_POSTS_FUFILLED"}
Received:
  {"payload": {Symbol(impl): {"message": "The string did not match the expected pattern.", "name": "SyntaxError", Symbol(wrapper): [Circular]}}, "type": "FETCH_POSTS_REJECTED"}

Difference:

- Expected
+ Received

  Object {
-   "type": "FETCH_POSTS_FUFILLED",
+   "payload": DOMException {
+     Symbol(impl): DOMExceptionImpl {
+       "message": "The string did not match the expected pattern.",
+       "name": "SyntaxError",
+       Symbol(wrapper): [Circular],
+     },
+   },
+   "type": "FETCH_POSTS_REJECTED",

jest反馈的图片形式如下：

Answer 1

您正在使用的模拟商店将存储已向其发出的所有分派调用。在您的情况下，应该进行两次调度调用，第一个是 FETCH_POSTS，第二个是 FETCH_POST_FULFILLED 或 FETCH_POST_REJECTED。

因此，当您从模拟存储中检索分派的操作时，第一个条目（您在 expect 中使用的条目）将是 FETCH_POSTS。您应该检查数组中的第二个值，它可以是 FETCH_POSTS_FULFILLED 或 FETCH_POSTS_REJECTED，具体取决于您正在测试的函数中承诺的解析方式。

为什么我的 jest async action creator 测试不起作用？

Why is my jest async action creator test not working?

unit-testing

jestjs

redux-mock-store