如何sinon间谍模块导出实用程序功能 [英] How to sinon spy module export utility functions

问题描述

在javascript（ES6）中，我有一个实用程序模块，它只包含一些函数，然后在文件的最后，我这样导出它们：

In javascript (ES6), I have a utility module which just contains some functions, and then in the end of the file, I export them like so:

module.exports = {
  someFunction1,
  someFunction2,
  someFunction3,
}

然后我想为这些函数编写单元测试。一些功能相互依赖;他们以某种方式相互调用，例如，someFunction1可能会调用someFunction2。没有循环问题。

Then I want to write unit tests for those functions. Some of the functions depend on each other; they call each other in a way, that for example, someFunction1 might call someFunction2. There's no circular problems.

一切正常，直到我需要监视其中一个函数被调用。我该怎么做？目前我正在使用Chai和Sinon。

Everything works well, until I need to spy that one of the functions is called. How can I do it? Currently I'm using Chai and Sinon.

在测试文件中，我将整个文件作为模块导入：

In the test file, I have imported the whole file as a module:

const wholeModule = require('path/to/the/js/file')

最后，我的测试如下：

it('should call the someFunction2', (done) => {
  const spy = sinon.spy(wholeModule, 'someFunction2')

  wholeModule.someFunction1() // someFunction2 is called inside someFunction1

  assert(spy.calledOnce, 'someFunction2 should be called once')
  done()
})

问题是，测试失败，因为在someFunction1中，someFunction2函数是直接使用的。我将间谍应用于模块对象的功能。但那是一个不同的对象。这是someFunction1的一个例子：

The problem is, that the test fails, because in someFunction1, the someFunction2 function is used directly. I apply the spy to the module object's function. But that's a different object. Here's an example of the someFunction1:

function someFunction1() {
  someFunction2()
  return 2;
}

我知道它不起作用的原因，但我不知道知道在这种情况下最好的做法是什么？请帮助！

I know the reason why it won't work, but I don't know what would be the best practise in this case to make it work? Please help!

推荐答案

您可以使用重新布线模块。以下是一个示例：

You can use rewire module. Here is an example:

源代码：

function someFunction1() {
  console.log('someFunction1 called')
  someFunction2();
}

function someFunction2() {
  console.log('someFunction2 called')
}

module.exports = {
  someFunction1: someFunction1,
  someFunction2: someFunction2
}

测试用例：

'use strict';

var expect = require('chai').expect;
var rewire = require('rewire');
var sinon = require('sinon');

var funcs = rewire('../lib/someFunctions');

it('should call the someFunction2', () => {
  var someFunction2Stub = sinon.stub();
  funcs.__set__({
    someFunction2: someFunction2Stub,
  });

  someFunction2Stub.returns(null);

  funcs.someFunction1();

  expect(someFunction2Stub.calledOnce).to.equal(true);
});

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