如何在玩笑中正确使用 axios.get.mockResolvedValue 进行异步调用

Question

我想用 Jest 模拟异步函数的 catch 块中的返回值

这是我正在为其编写单元测试的函数：

  try {

    make some axios request

    }

    return users;

  } catch (err) {

    return new Map();

  }

};

    it('should catch error when query is unsuccessful', async () => {

      axios.get.mockRejectedValue(new Map());

      const res = getUserDataByIds('someUserIds');

      await expect(res).rejects.toThrow();

    });

我从 Jest 收到错误消息：

 expect(received).rejects.toEqual()

 Received promise resolved instead of rejected

 Resolved to value: Map {}

我希望测试应该通过，因为我在嘲笑一个被拒绝的值。

Answer 1

您可以创建一个模拟函数来替换axios.get()方法。index.ts:import axios from 'axios';export async function getUserDataByIds(ids: string[]) {  try {    const users = await axios.get('/users');    return users;  } catch (err) {    return new Map();  }}index.spec.ts:import { getUserDataByIds } from './';import axios from 'axios';describe('getUserDataByIds', () => {  it('should return empty Map when axios.get failed', async () => {    const getError = new Error('network error');    axios.get = jest.fn().mockRejectedValue(getError);    const actualValue = await getUserDataByIds(['1']);    expect(actualValue).toEqual(new Map());    expect(axios.get).toBeCalledWith('/users');  });  it('should return users', async () => {    const mockedUsers = [{ userId: 1 }];    axios.get = jest.fn().mockResolvedValue(mockedUsers);    const actualValue = await getUserDataByIds(['1']);    expect(actualValue).toEqual(mockedUsers);    expect(axios.get).toBeCalledWith('/users');  });});100% 覆盖率的单元测试结果： PASS  src/stackoverflow/58273544/index.spec.ts  getUserDataByIds    ✓ should return empty Map when axios.get failed (12ms)    ✓ should return users (4ms)----------|----------|----------|----------|----------|-------------------|File      |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |----------|----------|----------|----------|----------|-------------------|All files |      100 |      100 |      100 |      100 |                   | index.ts |      100 |      100 |      100 |      100 |                   |----------|----------|----------|----------|----------|-------------------|Test Suites: 1 passed, 1 totalTests:       2 passed, 2 totalSnapshots:   0 totalTime:        5.597s, estimated 7s源代码：https : //github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/58273544