模拟需要(Ed)服务

Question

我试图使用sinon来模拟我的函数使用的服务，但是我无法找到将模拟注入到函数中的方法。

使用require获取服务

我的职能如下：

// something.js
const service = require('./service');
module.exports = {
    // do something using a service
    doSomething: function (options) {
        let results = [];
        return service.foo(option.param)
        // and return the value adding some logic
        .then(function(resultFromService){
            // want to test this flag
            if ( options.someFlag ) {
                results = resultFromService;
            }
        })
        .then(function(){
            /// more existing code here
            return results;
         });
    } 
}

我试图像这样嘲弄service.foo：

const something = require('../../something.js');
const sinon = require('sinon');  
...
it('should doSomething by calling foo in the service', function(done) {

     ///I'm getting this error here: Error: Trying to stub property 'foo' of undefined
     sinon.stub( something.service , 'foo' )
     .returns(when(function() {
         return ['bar', 'baz'];
     }));


     let promise = something.doSomething({param:'for service', someFlag:true});
});

然后检查我的doSomething方法是否确实在执行它应该执行的逻辑。

问:如何为该服务注入一个模拟服务和/或一个模拟函数，该服务在我的something函数中定义为一个私有闭包作用域变量。

Answer 1

我最终使用了mock-require

const mockRequire = require('mock-require');

it('do something', function(){
   mockRequire('./service', { 
      foo: function(p){
         return [];
      }
   });
   let something = require('./something.js); 
   // Now when it requires the service, it gets the mock instead
    something.doSomething({flag:true, param:'a'});
    assert. etc. etc
}));