如何使用jasmine-ajax验证是否调用了send方法？

Question

如果我从来没有调用过jasmine-ajax方法，那么onreadystatechange应该调用readyState为4的send吗？

如果上述情况不是预期的行为，我如何使用jasmine-ajax来验证是否调用了send方法？

以下是正在测试的代码：

    Loader = (function() {

      var loadNames = function(url, success_callback, error_callback) {

        var ajax = new XMLHttpRequest();

        ajax.open("GET", url);
        ajax.onreadystatechange = function () {
          console.log("Ready state is " + ajax.readyState);
          if (ajax.readyState === 4 && ajax.status === 200) {
            success_callback(JSON.parse(ajax.responseText));
          } else if (ajax.readyState === 4 && ajax.status !== 200) {
            error_callback("There was a problem. Status returned was " + ajax.status);
          }
        };

        ajax.onerror = function () {
         error_callback("Unknown error");
        };

        // Shouldn't removing the call to send prevent
        // onredystatechange from being called with readyState 4?
        // ajax.send();
      };

      return {
        loadNames: loadNames
      };

    })();

下面是测试结果：

describe("Loader", function () {

  var successFunction, failFunction;

  beforeEach(function () {
    jasmine.Ajax.install();
    successFunction = jasmine.createSpy("successFunction");
    failFunction = jasmine.createSpy("failFunction");
  });

  afterEach(function () {
    jasmine.Ajax.uninstall();
  });

  describe("#loadNames", function () {    
    it("Makes a success callback with the data when successful", function () {
      Loader.loadNames("someURL", successFunction, failFunction);
      jasmine.Ajax.requests.mostRecent().respondWith({
        "status": 200,
        "contentType": 'application/json',
        "responseText": '[1, 2, 4, 3, 5]'
      });

      // Shouldn't this fail since I never called send?
      expect(successFunction).toHaveBeenCalledWith([1, 2, 4, 3, 5]);
    });
  });
});

我很惊讶地看到successFunction被调用了，因为被测试的代码从来没有调用过ajax.send()。如果这是库的预期行为，那么如何对底层ajax对象执行spyOn操作，以便验证被测代码是否调用了send

Answer 1

是的，您没有调用ajax.send()，但是由于下面这段代码，您触发了ajax.onreadystatechange事件：

jasmine.Ajax.requests.mostRecent().respondWith({
  "status": 200,
  "contentType": 'application/json',
  "responseText": '[1, 2, 4, 3, 5]'
});

这会改变readystate并将readystate设置为done。这实际上正如文档中所说的那样：https://jasmine.github.io/2.6/ajax.html

至于如何检查xhr.send是否真的被调用，这个SO answer解释说，你可以在你的beforeEach中执行以下操作来监视它：

spyOn(XMLHttpRequest.prototype, 'send');

在加载器中取消对xhr.send()部分的注释后，您可以检查方法调用，如下所示：

describe("#loadNames", function () {    
  it("Makes a success callback with the data when successful", function () {
    Loader.loadNames("someURL", successFunction, failFunction);
    jasmine.Ajax.requests.mostRecent().respondWith({
      "status": 200,
      "contentType": 'application/json',
      "responseText": '[1, 2, 4, 3, 5]'
    });

    expect(XMLHttpRequest.prototype.open).toHaveBeenCalled();
  });
});