为什么这些Jest Mocks不会重置？

Question

我有测试代码影响其他测试并导致它们失败.当我孤立地运行测试用例时,一切都过去了,但是当我运行整个套装时,会有很多失败.如果你看下面的两个测试,你可以看到我在测试中覆盖了一个模拟模块,导致抛出异常.

HttpService.post = jest.fn(() => {
   return Promise.reject({ payload: 'rejected' });
});

在运行此行之后,所有需要原始HttpService.post模拟的测试都会失败,因为它们未被重置.在测试之后,如何正确地将我的模拟恢复到导入的模拟？我已经尝试jest.resetMock过beforeEach和类似于每个jest方法,但没有任何效果.我知道答案可能是直截了当的,但我对我在网上读到的有关如何导入代码的所有差异感到困惑(es6 import,commonJs).谢谢!

import HttpService from '../../services/httpService';
import handleErrors from '../../utilities/handleErrors';

jest.mock('../../services/httpService');
jest.mock('../../utilities/handleErrors');

describe('async actions', () => {

  beforeEach(() => {
    store = mockStore({});
  });

  describe('some describe that wraps both tests', () => {

    describe('a describe that wraps just the first test', () => {
      test(`creates ${constants.actions.REQUEST_SAVE_NOTE_FAILURE}`, () => {
        HttpService.post = jest.fn(() => {
          return Promise.reject({ payload: 'rejected' });
        });
        const expectedActions = [
          { type: constants.actions.REQUEST_SAVE_NOTE },
          { type: constants.actions.REQUEST_SAVE_NOTE_FAILURE, data: { payload: 'rejected' } },
        ];
        return store.dispatch(actions.saveNote({
          id: 1,
          note: 'note',
        })).then(() => {
          expect(store.getActions()).toEqual(expectedActions);
        });
      });
    });

    describe('a describe that wraps just the second test', () => {
      test(`creates ${constants.actions.REQUEST_SAVE_NOTE}
        and ${constants.actions.RECEIVE_SAVE_NOTE}`, () => {
        params = {
          body: {
            prospects: [1],
            note: 'note',
          },
        };
        const expectedActions = [
          { type: constants.actions.REQUEST_SAVE_NOTE },
          { type: constants.actions.RECEIVE_SAVE_NOTE, data: { payload: 'payload' } },
        ];

        return store.dispatch(actions.saveNote({
          id: 1,
          note: 'note',
        })).then(() => {
          expect(store.getActions()).toEqual(expectedActions);
          expect(HttpService.post).toBeCalledWith({ ...params, url: '/api/prospect/add-note' });
        });
      });
    });

  })

});

Answer 1

如果导入作为对象的模块,则需要独立模拟每个导出的函数:

import HttpService from '../../services/httpService';
jest.mock('../../services/httpService', ()=>({
  post: jest.fn()
});

稍后您可以像这样设置模拟的行为

HttpService.post.mockImplementation(()=>Promise.reject({ payload: 'rejected' }))

并重置

HttpService.post.mockReset()