用 mocha chai 和 sinon 测试 promise

Question

我想使用mocha、chai 和sinon 测试我的承诺解析处理程序和承诺拒绝处理程序。此外，我已经设置了sinon-chai 插件和sinon-stub-promise 插件。

这是我的要求语句块：

var chai = require('chai');
var expect = chai.expect;
var sinonChai = require('sinon-chai');
chai.use(sinonChai);
var sinon = require('sinon');
var sinonStubPromise = require('sinon-stub-promise');
sinonStubPromise(sinon);

这是我的测试套件：

describe('Connect to github users',function(done){

    var api = require('../users'),
        onSuccess = api.onSuccess,
        onError = api.onReject; 
    console.dir(api);
    //the idea is not to test the async connection,the idea is to test 
    //async connection but to test how the results are handled.
    var resolveHandler,
        rejectHandler,
        getPromise,
        result;

    beforeEach(function(){
        resolveHandler = sinon.spy(onSuccess);
        rejectHandler = sinon.spy(onError);
        getPromise = sinon.stub().returnsPromise();
    });

    it('must obtain the result when promise is successful',function(){
        result = [...];//is an actual JSON array    
        getPromise.resolves(result);

        getPromise()
            .then(resolveHandler)
            .catch(rejectHandler);

        expect(resolveHandler).to.have.been.called();//error 
        expect(resolveHandler).to.have.returned(result);
        expect(rejectHandler).to.have.not.been.called();    
        done();
    });

    afterEach(function(){
        resolveHandler.reset();
        rejectHandler.reset();
        getPromise.restore();
    });

});

我发现自己遇到了这个错误：

 Connect to github users must obtain the result when promise is successful:
 TypeError: expect(...).to.have.been.called.toEqual is not a function
  at Context.<anonymous> (C:\Users\vamsi\Do\testing_promises\test\githubUsersSpec.js:94:46)

Answer 1

sinon-with-promise 包应该适合您正在尝试做的事情。我遇到了同样的问题（除了我不需要测试拒绝案例）并且效果很好。

Answer 2

这里这行代码是错误的：

expect(resolveHandler).to.have.been.called();

called 只是spy 上的一个属性，其值始终为boolean，可以像这样使用chai 进行简单测试：

expect(resolveHandler.called).to.equal(true);

类似地代替这一行来确认函数没有被拒绝：

expect(rejectHandler).to.have.not.been.called();

将此与called 一起用作属性：

expect(rejectHandler.called).to.equal(false);