Answer by R01010010 for What's the difference between a mock & stub?

To be very clear and practical:

Stub: A class or object that implements the methods of the class/object to be faked and returns always what you want.

Example in JavaScript:

var Stub = {   method_a: function(param_a, param_b){      return 'This is an static result';   }}

Mock: The same of stub, but it adds some logic that "verifies" when a method is called so you can be sure some implementation is calling that method.

As @mLevan says imagine as an example that you're testing a user registration class. After calling Save, it should call SendConfirmationEmail.

A very stupid code Example:

var Mock = {   calls: {      method_a: 0   }   method_a: function(param_a, param_b){     this.method_a++;      console.log('Mock.method_a its been called!');   }}