Question

我正在试图窥探原生的WebSocket构造函数，所以我写道：

it("should spy and call through WebSocket constructor", function (done) {
  var WSspy = spyOn(window, "WebSocket").and.callThrough();

  var ws = new WebSocket("ws://some/where");

  expect(WSspy).to.toHaveBeenCalledWith("ws://some/where");
});

但会导致错误：

TypeError: Failed to construct 'WebSocket': Please use the 'new' operator, this DOM object constructor cannot be called as a function.

我应该callThrough这样的构造函数？

Answer 1

我找到了callFake的解决方法：

it("should spy and callFake WebSocket constructor", function (done) {
  var realWS = WebSocket;  
  var WSSpy = spyOn(window, "WebSocket").and.callFake(function(url,protocols){
    return new realWS(url,protocols);
  });        

  var ws = new WebSocket("ws://some/where");

  expect(WSSpy).toHaveBeenCalledWith("ws://some/where");
  done();
});

它工作得很好，但它会覆盖WebSocket.prototype，所以请确保在创建间谍之前使用它或保存引用，如

var realWS = WebSocket;  
var messageSpy = spyOn(WebSocket.prototype, "close").and.callThrough();      
var WSSpy = spyOn(window, "WebSocket").and.callFake(function(url,protocols){
  return new realWS(url,protocols);
});

间谍和callThrough与Jasmine的本机WebSocket构造函数

1 个答案: