React Js API 调用 Jest 测试用例？答案

【问题标题】：React Js API call Jest Test Case?React Js API 调用 Jest 测试用例？
【发布时间】：2021-10-16 15:52:48
【问题描述】：

我正在尝试为我的API调用函数编写测试用例，我不知道我无法成功运行测试的错误在哪里是API调用函数代码和测试用例代码。

export async function getUserTest() {
    fetch(config.apiUrl.myFleetAPI, {
        method: 'GET',
        headers: {
            Accept: 'application/json',
            'Content-Type': 'application/json',
            Authorization: 'Bearer ' + 'GcGs5OF5TQ50sbjXRXDDtG8APTSa0s'
        }
    })
        .then((response) => {
            return response.json();
        })
        .catch((reject) => console.log(reject));
    
}

测试用例代码。

从“反应”导入反应；从 '../Service/Dashboard/Dashboard' 导入 { getUserTest };

global.fetch = jest.fn();
const mockAPICall = (option, data) => global.fetch.mockImplementation(() => Promise[option](data));

describe('Car Components component', () => {
    describe('when rendered', () => {
        it('should call a fetchData function', async () => {
            const testData = { current_user: 'Rahul Raj', name: 'Lafarge' };

            mockAPICall('resolve', testData);
            return getUserTest().then((data) => {
                expect(data).toEqual(testData);
            });
        });
    });
});

这是我在尝试运行测试用例时遇到的错误。

 Car Components component
    when rendered
      ✕ should call a fetchData function (5 ms)

  ● Car Components component › when rendered › should call a fetchData function

    expect(received).toEqual(expected) // deep equality

    Expected: {"current_user": "Rahul Raj", "name": "Lafarge"}
    Received: undefined

      65 |             mockAPICall('resolve', testData);
      66 |             return getUserTest().then((data) => {
    > 67 |                 expect(data).toEqual(testData);
         |                              ^
      68 |             });
      69 |         });
      70 |     });

      at src/Test/MainScreen.test.js:67:30

  console.log
    TypeError: response.json is not a function
        at /Users/rahulraj/Documents/Workproject/Vivafront/lafargeClone/src/Service/Dashboard/Dashboard.js:44:29
        at processTicksAndRejections (internal/process/task_queues.js:93:5)

【问题讨论】：

标签： javascript reactjs unit-testing react-testing

【解决方案1】：

你的代码有两个问题：

fetch 函数的解析值是Response，它有一个.json() 方法，你忘了模拟它。
你忘了像return fetch(/.../)一样返回承诺。这会导致测试用例中的promise链不等待fetch promise完成，这就是为什么返回结果是undefined

例如

api.js:

const config = {
  apiUrl: {
    myFleetAPI: 'http://localhost:3000/api',
  },
};
export async function getUserTest() {
  return fetch(config.apiUrl.myFleetAPI, {
    method: 'GET',
    headers: {
      Accept: 'application/json',
      'Content-Type': 'application/json',
      Authorization: 'Bearer ' + 'GcGs5OF5TQ50sbjXRXDDtG8APTSa0s',
    },
  })
    .then((response) => {
      return response.json();
    })
    .catch((reject) => console.log(reject));
}

api.test.js:

import { getUserTest } from './api';

describe('68771600', () => {
  test('should pass', () => {
    const testData = { current_user: 'Rahul Raj', name: 'Lafarge' };

    const response = { json: jest.fn().mockResolvedValueOnce(testData) };
    global.fetch = jest.fn().mockResolvedValueOnce(response);

    return getUserTest().then((data) => {
      expect(data).toEqual(testData);
    });
  });
});

测试结果：

 PASS  examples/68771600/api.test.js (9.885 s)
  68771600
    ✓ should pass (3 ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |      80 |      100 |   66.67 |      80 |                   
 api.js   |      80 |      100 |   66.67 |      80 | 18                
----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        10.794 s

【讨论】：