Object methods, "this": Missing appropriate tests for chaining exercise

[Omid-Heydarzadeh]

Article

Object methods, "this"

There are missing tests for the "chaining" exercise on the "Object methods, this" article to ensure that the showStep method returns this.

Suggested tests:

 it('showStep() should return this', function() {
   assert(ladder.showStep(), ladder);
 });

 it('up().up().down().showStep().down().showStep()', function () {
   assert.equal(ladder.up().up().down().showStep().down().showStep().step, 0)
 })

[iliakan]

Might be good. Make a PR, please?