Question

使用笑话进行测试时，我具有基本的测试服语法：

jest.mock('axios');

describe('app', () => {
    let render

    beforeEach(() => {
        axiosMock.get.mockResolvedValueOnce({
            data: {greeting: 'hello there'},
        }),
        render= renderApp()
    });

    test('should render something', () => {
        expect(something).toBeInTheDocument();
    });


});

问题是我的代码中有拦截器，当使用jest命令输出运行测试时，这些拦截器是

TypeError：无法读取未定义的属性“拦截器”

并指向拦截器对象

axiosInstance.interceptors.request.use(...

axiosInstance是一个变量，用于存储axios.create的返回值

export const axiosInstance = axios.create({...

在SO How do I test axios in jest上引用了该axios线程，但是它不涉及任何拦截器，因此并没有真正的帮助。

Answer 1

这足够了

jest.mock('axios', () => {
    return {
        interceptors: {
            request: { use: jest.fn(), eject: jest.fn() },
            response: { use: jest.fn(), eject: jest.fn() },
        },
    };
});

Answer 2

确保模拟出拦截器和axios.create（如果使用）：

// Replace any instances with the mocked instance (a new mock could be used here instead):
axios.create.mockImplementation((config) => axios);

// Mock out the interceptor (assuming there is only one):
let requestCallback = () => {
  console.log("There were no interceptors");
};
axios.interceptors.request.use.mockImplementation((callback) => {
  requestCallback = callback;
});

// Mock out the get request so that it returns the mocked data but also calls the 
// interceptor code:
axios.get.mockImplementation(() => {
  requestCallback();
  return {
    data: "this is some data"
  };
});

注意，如果这不起作用：

此示例假定create和interceptor调用位于Jest可以模拟它们的位置。将axios.create或axiosInstance.interceptors.request.use行放在函数范围之外可能会导致上述模拟失败。这是一个示例文件，Jest可以在其中模拟它们：

const axios = require('axios');

const DEBUG = true;

const customRequest = (url) => {
  // Example of axios.create from https://www.npmjs.com/package/axios#axioscreateconfig
  const axiosInstance = axios.create({
    baseURL: 'https://some-domain.com/api/',
    timeout: 1000,
    headers: {'X-Custom-Header': 'foobar'}
  });

  // Example of interceptor taken from https://stackoverflow.com/a/52737325/7470360:
  axiosInstance.interceptors.request.use((config) => {
    if (DEBUG) { console.info("Request called", config); }
    return config;
  }, (error) => {
    if (DEBUG) { console.error("Request error ", error); }
    return Promise.reject(error);
  });

  return axiosInstance.get(url);
}

module.exports = customRequest;

模拟代码将模拟axios.create中的axiosInstance调用和customRequest中的{{1}}调用。将创建或拦截移动到函数外部将导致模拟失败。

Answer 3

这是我嘲笑 axios.create 及其 interceptors 的方式：

jest.mock('axios', () => {
  return {
    create: () => {
      return {
        interceptors: {
          request: {eject: jest.fn(), use: jest.fn()},
          response: {eject: jest.fn(), use: jest.fn()},
        },
      };
    },
  };
});

之后我可以在我的测试代码中调用以下内容：

const client = axios.create({
  baseURL: 'http://some-url.com',
});

client.interceptors.request.use(config => {
  // some other test code
  return config;
});

使用jest.mock（'axios'）时如何模拟拦截器？

3 个答案: