Question

我有以下功能：

function getPersonData(id) {
  retrieveData(
    id,
    function(person) {
      if(person.name) {
        displayPerson(person);
      }
    }
}

function retrieveData(id, successCallBack) {
    executeRequest(id, {
      success: successCallBack
    });
}

getPersonData根据ID检索某人的信息。它通过传入id和successCallBack函数来调用retrieveData。

retrieveData获取id和successCallBack并调用另一个函数executeRequest，该函数获取数据并传回一个person对象。

我正在尝试测试getPersonData并设置以下规范

describe("when getPersonData is called with the right person id", function() {
  beforeEach(function() {
    spyOn(projA.data, "retrieveData").and.returnValue(
      {
        'name': 'john'
      }
    );
    spyOn(projA.data, "displayPerson");
    projA.data.getPersonData("123");
  });

  it("displays the person's details", function() {
    expect(projA.data.displayPerson).toHaveBeenCalled();
  );
});

但是当执行规范时，不会调用displayPerson方法。这是因为即使我模拟function(person)返回结果，也没有传入从成功callBack retrieveData传回的人员数据。

我的问题是：这是测试callBack函数的正确方法吗？无论哪种方式，我做错了什么？

Answer 1

好的，所以茉莉花在很多细微的方面很棘手，我认为你的代码存在两个主要问题

你有太多的异步调用相互包装。这本身不是一个问题，但它使JASMINE的测试变得更加困难。例如，使用retrieveData函数调用executeRequest函数具有完全相同的参数但方式略有不同，这有什么意义。

我重写了你的getPersonData就像这样

function getPersonData(id) {
  // this is needed to properly spy in Jasmine
  var self = this;

  //replaced retrieveData with just execute request
  // self is required to properly spy in Jasmine
  self.executeRequest(id, {
    success: function(person) {
     if (person.name) {
      self.displayPerson(person);
     }
    }
  })
}

//I don't know what exactly executeRequest does 
//but I took the liberty to just make it up for this example 
function executeRequest(id, callback) {
 callback.success({
   name: id
  });
}

//I also assumed that projA would look something like this
var projA = {
 data: {
  getPersonData: getPersonData,
  retrieveData: retrieveData,
  displayPerson: displayPerson,
  executeRequest: executeRequest
 }
};

2。为了测试Jasmine中的异步代码，您需要在测试中包含done回调。此外，如果您希望自动触发回调函数，则需要在setTimeout函数内进行设置，否则它将永远不会触发。这是一个经过调整的例子：

    describe("when getPersonData is called with the right person id",  function() {
     beforeEach(function() {
      //you should not spyOn retriveData or executeCode because it will override the function you wrote and will never call displayPerson

      // you should only have spies on the methods you are testing otherwise they will override other methods
      spyOn(projA.data, "displayPerson");
     });

     it("displays the person's details", function(done) {
      // it's better to call the function within specific test blocks so you have control over the test
      projA.data.getPersonData("123");

      // at this point, it will just have called the getPersonData but will not call executeRequest
      setTimeout(function() {
       //this block will just call executeRequest
       setTimeout(function() {
        //this block will finally call displayPerson
        expect(projA.data.displayPerson).toHaveBeenCalled();

        //tell jasmine the test is done after this
        done();
        })
       })
     });
    })

使用jasmine测试JavaScript回调函数

1 个答案: