Use the Jasmine spy's mostRecentCall element to get the arguments of a test invocation

jasmine-spy-mostRecentCall

/*
 * Let's say we have a collaborater with a 'show' function.  The instance under test is going to invoke
 * this function and pass two arguments: 'parameters' and a callback function.  We often want to either
 * do some inspection on the 'parameters' to make sure they're right, or invoke the callback to verify
 * behavior after the callback, such as after an XHR returns.
 */
describe("someFunctionThatInvokesOurCollaborator", function () {

  var instance,
      TemplateResource;
  
  beforeEach(function () {
    //create a spy with a 'show' function
    TemplateResource = jasmine.createSpyObj("TemplateResource", ["show"]);
    
    // assign the spy to the instance (it probably won't look like this)
    instance = new MyObjectUnderTest(TemplateResource);
  
    // excercise the behavior under test
    instance.someFunctionThatInvokesTemplateResourceDotShow();
  });
  
  it("should pass the correct parameters", function () {
  
    // verify that our first 'parameters' argument is correct
    var args = TemplateResource.show.mostRecentCall.args;
    expect(args[0]).toEqual("theRightParameters");
  });

  it("should do the right thing after the callback is invoked", function () {
    // invoke the callback so we can verify behavior that happens after the callback is invoked
    var args = TemplateResource.show.mostRecentCall.args,
        callback = args[1];

    callback();
  
    // other assertions that happen after the callback
    expect(instance.someSideEffectOfTheCallback).toBeTruthy();
  });

});