Jasmine 2 Spy Cheat Sheet

If you’re tired of Googling for the Jasmine docs every time you need to use a spy, look no further!

Jasmine is my testing framework of choice when I’m writing Angular. And I was just getting used to all those spy methods with the help of Toby Ho’s cheat sheet, and then Jasmine 2 came along and changed all the method names.

So here’s an updated cheat sheet for spying with Jasmine 2.

Create a spy

Spy on an existing method

spyOn(obj, 'method');   // same as Jasmine 1

Create a new function to use as a spy

jasmine.createSpy('optional name');    // same as Jasmine 1

Create a new object with spy functions as properties

jasmine.createSpyObj('name', ['fn1', 'fn2', ...]);    // same as Jasmine 1

Modify Behavior When the spy is Called

Default spy behavior is to record the call with its context/arguments and stop there. Spies will not call through to the spied function by default. These calls all modify that behavior.

Call through to the original

obj.method.and.callThrough();

Return the specified value

obj.method.and.returnValue(val);

Call the given function instead of the real one

obj.method.and.callFake(function() {...});

Throw an error

obj.method.and.throwError(err);

Reset to default stubbing behavior (resets the operations above)

obj.method.and.stub();

Verifying and Counting Calls on a spy

Every call to a spy is exposed on the calls property

Returns true if any calls have been made

obj.method.calls.any();

Returns the number of times the spy got called

obj.method.calls.count();

Reset the call tracker

obj.method.calls.reset();

After calling reset(), any() will be false, count() will be 0, etc.

Returns the first call’s context and arguments

obj.method.calls.first();

It will return an object like this:

{
  object: {...},  // 'this' object
  args: []        // array of arguments
}

Returns the most recent call’s context and arguments

obj.method.calls.mostRecent();

It will return an object like this:

{
  object: {...},  // 'this' object
  args: []        // array of arguments
}

Returns array of context and arguments passed to each call

obj.method.calls.all();

The returned array looks like this:

[
  {
    object: {...},  // 'this' object
    args: [...]     // array of arguments
  },  
  ...               // one object for each call
]

That’s it! Go test some stuff.

Jasmine 2 Spy Cheat Sheet was originally published by Dave Ceddia at Angularity on September 30, 2015.

CodeProject