如何使用 sinon/mocha 模拟 npm 模块 [英] How to mock npm module with sinon/mocha

问题描述

我正在尝试测试一个调用模块 cors 的函数.我想测试 cors 是否会被调用.为此，我必须存根/模拟它.

I'm trying to test a function that calls the module cors. I want to test that cors would be called. For that, I'd have to stub/mock it.

这是函数cors.js

Here is the function cors.js

const cors = require("cors");

const setCors = () => cors({origin: 'http//localhost:3000'});
module.exports = { setCors }

我测试此类功能的想法类似于

My idea of testing such function would be something like

cors.test.js

cors.test.js

  describe("setCors", () => {
    it("should call cors", () => {
      sinon.stub(cors)

      setCors();
      expect(cors).to.have.been.calledOnce;

    });
  });

知道如何存根 npm 模块吗?

Any idea how to stub npm module?

推荐答案

您可以使用 mock-require 或 proxyquire

mock-require

const mock = require('mock-require')
const sinon = require('sinon')

describe("setCors", () => {
  it("should call cors", () => {
    const corsSpy = sinon.spy();
    mock('cors', corsSpy);

    // Here you might want to reRequire setCors since the dependancy cors is cached by require
    // setCors = mock.reRequire('./setCors');

    setCors();
    expect(corsSpy).to.have.been.calledOnce;
    // corsSpy.callCount should be 1 here

    // Remove the mock
    mock.stop('cors');
  });
});

如果您愿意，您可以在每个测试之间使用 corsSpy.reset() 在描述和重置间谍之上定义模拟，而不是为每个测试模拟和停止模拟.

If you want you can define the mock on top of describe and reset the spy using corsSpy.reset() between each tests rather than mocking and stopping the mock for each tests.

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