javascript - 在Jest中模拟 shell 命令输出

我正在编写一个cli工具，并试图在Jest中为其编写测试。我有一些调用git的函数，但是我需要模拟这些调用的返回值，否则它们将不一致。

我用来调出外壳的代码如下所示。

import { exec } from "child_process";

function execute(command) {
  return new Promise((resolve, reject) => {
    exec(command, resolve);
  });
}

export const getGitDiff = function () {
  return execute("git diff")
};

如何在Jest中为此编写测试？

我试过的是

import { getGitDiff } from './getGitDiff';

describe('get git diff', () => {
  it('should send "git diff" to stdin', () => {
    const spy = jest.spyOn(process.stdin, 'write');
    return getGitDiff().then(() => {
      expect(spy).toHaveBeenCalled();
    })
  });
});

最佳答案

我最终创建了一个名为child_process.js的新文件，并在Jest中使用genMockFromModule功能对整个模块进行存根，并重新实现了某些类似这样的功能

const child_process = jest.genMockFromModule('child_process');

const mockOutput = {}

const exec = jest.fn().mockImplementation((command, resolve) => {
    resolve(mockOutput[command]);
})

const __setResponse = (command, string) => {
    mockOutput[command] = string;
}

child_process.exec = exec
child_process.__setResponse = __setResponse;

module.exports = child_process;

我有一个像

const child_process = jest.genMockFromModule('child_process');

const mockOutput = {}

const exec = jest.fn().mockImplementation((command, resolve) => {
    resolve(mockOutput[command]);
})

const __setResponse = (command, string) => {
    mockOutput[command] = string;
}

child_process.exec = exec
child_process.__setResponse = __setResponse;

module.exports = child_process;