如何模拟公理类

Question

我正在为我的异步操作编写测试。我已经将我的 axios 调用抽象到一个单独的类中。如果我想测试我的异步 redux 操作，如何为api.js编写模拟以使sampleAction.test.js通过？谢谢！

API.js：

import axios from 'axios';
let apiUrl = '/api/';
if (process.env.NODE_ENV === 'test') {
  apiUrl = 'http://localhost:8080/api/';
}
export default class Api {
  static async get(url) {
    const response = await axios.get(`${apiUrl}${url}`, {withCredentials: true});
    return response;
  }
}

示例操作.js： 从"./api"导入 API;

export const fetchData = () => async (dispatch) => {
  try {
    const response = await Api.get('foo');
    dispatch({
      type: 'RECEIVE_DATA',
      data: response.data.data,
    });
  } catch (error) {
    handleError(error);
  }
};

sampleAction.test.js：

import store from './store';
test('testing RECEIVE_DATA async action', () => {
  const expectedActions = [
    { type: 'RECEIVE_DATA', data: 'payload' },
  ];
  return store.dispatch(actions.fetchData()).then(() => {
    expect(store.getActions()).toEqual(expectedActions);
  });
});

Answer 1

你可以

这样模拟Api.get：

import { fetchData } from './sampleAction';
import Api from './api';
let getMock;
beforeEach(() => {
  getMock = jest.spyOn(Api, 'get');
  getMock.mockResolvedValue({ data: { data: 'mock data' } });
});
afterEach(() => {
  getMock.mockRestore();
});
test('testing RECEIVE_DATA async action', async () => {
  const dispatch = jest.fn();
  await fetchData()(dispatch);
  expect(getMock).toHaveBeenCalledWith('foo');  // Success!
  expect(dispatch).toHaveBeenCalledWith({
    type: 'RECEIVE_DATA',
    data: 'mock data'
  });  // Success!
});

---

。或者你可以像这样模拟api.js：

import { fetchData } from './sampleAction';
import Api from './api';
jest.mock('./api', () => ({
  get: jest.fn(() => Promise.resolve({ data: { data: 'mock data' } }))
}));
test('testing RECEIVE_DATA async action', async () => {
  const dispatch = jest.fn();
  await fetchData()(dispatch);
  expect(Api.get).toHaveBeenCalledWith('foo');  // Success!
  expect(dispatch).toHaveBeenCalledWith({
    type: 'RECEIVE_DATA',
    data: 'mock data'
  });  // Success!
});

---

。或者您可以自动模拟api.js并填写Api.get的返回值：

import { fetchData } from './sampleAction';
import Api from './api';
jest.mock('./api');  // <= auto-mock
Api.get.mockResolvedValue({ data: { data: 'mock data' } });
test('testing RECEIVE_DATA async action', async () => {
  const dispatch = jest.fn();
  await fetchData()(dispatch);
  expect(Api.get).toHaveBeenCalledWith('foo');  // Success!
  expect(dispatch).toHaveBeenCalledWith({
    type: 'RECEIVE_DATA',
    data: 'mock data'
  });  // Success!
});

---

。或者您可以在./__mocks__/api.js创建手动模拟：

export default {
  get: jest.fn(() => Promise.resolve({ data: { data: 'mock data' } }))
}

。并在测试中激活它，如下所示：

import { fetchData } from './sampleAction';
import Api from './api';
jest.mock('./api');  // <= activate manual mock
test('testing RECEIVE_DATA async action', async () => {
  const dispatch = jest.fn();
  await fetchData()(dispatch);
  expect(Api.get).toHaveBeenCalledWith('foo');  // Success!
  expect(dispatch).toHaveBeenCalledWith({
    type: 'RECEIVE_DATA',
    data: 'mock data'
  });  // Success!
});