Using Jasmine to spy on variables in a function

Question

Suppose I have a function as follows

function fun1(a) {
  var local_a = a;
  local_a += 5;
  return local_a/2;
}

Is there a way to test for the value of local_a being what it should be (for example in the first line of code)? I'm a bit new to Jasmine, so am stuck. Thanks in advance.

Solution

Not really. You can do the following though:

Test the result of fun1():

expect(fun1(5)).toEqual(5);

Make sure it's actually called (useful if it happens through events) and also test the result:

var spy = jasmine.createSpy(window, 'fun1').andCallThrough();
fire_event_calling_fun1();
expect(spy).toHaveBeenCalled();
expect(some_condition);

Really reproduce the whole function inspecting intermediate results:

var spy = jasmine.createSpy(window, 'fun1').andCallFake(function (a) {
  var local_a = a;
  expect(local_a).toEqual(a);
  local_a += 5;
  expect(local_a).toEqual(a+5);
  return local_a/2;
});
fun1(42);
expect(spy).toHaveBeenCalled();

Comments

[Chetter Hummin]

I kind of suspected this would be the case. But thanks for the detailed answer. The second approach was new for me!

[ggozad]

Ah glad you liked it. You can see more about spies at github.com/pivotal/jasmine/wiki/Spies and pivotal.github.com/jasmine/jsdoc/symbols/jasmine.Spy.html