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

这是解决方案：

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';

jest.mock('axios');

describe('getUserDataByIds', () => {
  afterEach(() => {
    jest.resetAllMocks();
  });
  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 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        5.597s, estimated 7s

源代码：https : //github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/58273544