使用Jest

Question

我正在用玩笑编写单元测试。如何测试axios.post？我调查了所有内容，但几乎每个人都有使用axios.get的示例，但没有发布的示例。

 handleLogout(event) {
    event.preventDefault();
    axios
      .post("/logout")
      .then(function(response) {
        window.location = "/login";
      })
      .catch(function(error) {
        console.log(error);
      });

此方法由按钮onclick事件触发。

<button
    type="button"
    value="Logout"
    onClick={this.handleLogout}
  >
    Logout
  </button>

我怎么能在这种情况下编写一个测试用例？

编辑1：

  it("testing for axios", () => {
wrapper.simulate(
  "click",
  {
    preventDefault: () => {}
  },
);
console.log("here");
expect.assertions(1);

它给我错误“ TypeError：_axios2.default.post不是函数”

如果我不模拟阻止默认设置，它将显示“ TypeError：无法读取未定义的属性'preventDefault'”。 所以我认为在处理preventDefault（）之后，我需要以某种方式模拟axios。我在正确的道路上吗？该如何解决？

Answer 1

这是解决方案：

index.tsx：

import React from 'react';
import axios from 'axios';

export class SomeComponent extends React.Component {
  constructor(props) {
    super(props);
    this.handleLogout = this.handleLogout.bind(this);
  }
  public render() {
    return (
      <div>
        <button type="button" value="Logout" onClick={this.handleLogout}>
          Logout
        </button>
      </div>
    );
  }

  private handleLogout(event: React.MouseEvent<HTMLButtonElement>) {
    event.preventDefault();
    axios
      .post('/logout')
      .then(response => {
        console.log(response);
      })
      .catch(error => {
        console.log(error);
      });
  }
}

单元测试：

index.spec.tsx：

import React from 'react';
import { shallow } from 'enzyme';
import axios from 'axios';
import { SomeComponent } from './';

jest.mock('axios', () => {
  return {
    post: jest.fn()
  };
});

describe('SomeComponent', () => {
  describe('#handleLogout', () => {
    const mockedMouseEvent = {
      preventDefault: jest.fn()
    };
    it('should logout correctly', done => {
      const mockedData = 'mocked data';
      const wrapper = shallow(<SomeComponent></SomeComponent>);
      expect(wrapper.find('button')).toHaveLength(1);
      (axios.post as jest.MockedFunction<typeof axios.post>).mockResolvedValueOnce(mockedData);
      const consoleLogSpyOn = jest.spyOn(console, 'log');

      wrapper.find('button').simulate('click', mockedMouseEvent);
      expect(wrapper.find('button').text()).toBe('Logout');
      expect(axios.post).toBeCalledWith('/logout');

      setImmediate(() => {
        expect(consoleLogSpyOn).toBeCalledWith(mockedData);
        consoleLogSpyOn.mockRestore();
        done();
      });
    });

    it('should throw error when axios post error', done => {
      const mockedError = new Error('network error');
      const wrapper = shallow(<SomeComponent></SomeComponent>);
      expect(wrapper.find('button')).toHaveLength(1);
      (axios.post as jest.MockedFunction<typeof axios.post>).mockRejectedValueOnce(mockedError);
      const consoleLogSpyOn = jest.spyOn(console, 'log');
      wrapper.find('button').simulate('click', mockedMouseEvent);
      expect(wrapper.find('button').text()).toBe('Logout');
      expect(axios.post).toBeCalledWith('/logout');

      setImmediate(() => {
        expect(consoleLogSpyOn).toBeCalledWith(mockedError);
        consoleLogSpyOn.mockRestore();
        done();
      });
    });
  });
});

覆盖率100％的单元测试结果：

 PASS  src/stackoverflow/54555039/index.spec.tsx
  SomeComponent
    #handleLogout
      ✓ should logout correctly (29ms)
      ✓ should throw error when axios post error (14ms)

  console.log node_modules/jest-mock/build/index.js:860
    mocked data

  console.log node_modules/jest-mock/build/index.js:860
    Error: network error
        at Object.<anonymous> (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/src/stackoverflow/54555039/index.spec.tsx:36:27)
        at resolve (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/node_modules/jest-jasmine2/build/queueRunner.js:43:12)
        at new Promise (<anonymous>)
        at mapper (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/node_modules/jest-jasmine2/build/queueRunner.js:26:19)
        at promise.then (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/node_modules/jest-jasmine2/build/queueRunner.js:73:41)

-----------|----------|----------|----------|----------|-------------------|
File       |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
-----------|----------|----------|----------|----------|-------------------|
All files  |      100 |      100 |      100 |      100 |                   |
 index.tsx |      100 |      100 |      100 |      100 |                   |
-----------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        4.483s, estimated 5s

以下是完整的演示：https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/54555039