Jasmine: Ajax and Spies

In continuation of previous post for Jasmine, here I want to share my experience with Jasmine and Ajax. I want to show how cool it is with jasmine to test ajax calls in javascript. Jasmine spies can be used for mock the ajax call with fake data. Spy replaces the function it is spying on. For example my javascript function have an ajax call –

function myprofiledetails(){
    $.ajax({
      type: "GET",
      url: "http://vishnuatrai.com/aboutme.php",
      success: function(json){
        $('#infodiv').html("Ruby On Rails development with jasmine");
      }
   });
}

In spec file I can spy the ajax call in beforeEach function. And so it won’t make a server call and return the fake data.

describe("mock about me", function() {

  beforeEach(function() {
    //mocking ajax call with Jasmine Spies
    var fakeData = "Hi, I am doing Ruby On Rails development with jasmine";
    spyOn($, "ajax").andCallFake(function(params) {
      params.success(fakeData);
    });
  });

  it("Should have a Happy Face", function() {
    myprofiledetails();
    expect($('#infodiv')).toHaveText("Ruby On Rails development with jasmine");
  });
});

Jasmine provides some useful methods to support spies.

expect(x).toHaveBeenCalled()
passes if x is a spy and was called

expect(x).toHaveBeenCalledWith(arguments)
passes if x is a spy and was called with the specified arguments

expect(x).not.toHaveBeenCalled()                       
passes if x is a spy and was not called

expect(x).not.toHaveBeenCalledWith(arguments)   
passes if x is a spy and was not called with the specified arguments

Spies can be trained to respond in a variety of ways when invoked:

spyOn(x, 'method').andCallThrough():
spies on AND calls the original function spied on

spyOn(x, 'method').andReturn(arguments):
returns passed arguments when spy is called

spyOn(x, 'method').andThrow(exception):
throws passed exception when spy is called

spyOn(x, 'method').andCallFake(function): 
calls passed function when spy is called

There is a detailed wiki page for spices on github https://github.com/pivotal/jasmine/wiki/Spies.