It is rare that I see masterpieces on CodeReview, but this was one that warrants incredible kudos:

We have already outlined in a previous post, what a stub is, and the benefits of unit testing.

Please do the sample questions if you really want to learn this stuff

I see this problem all too often in stack overflow: a situation where folks check for the type of a class in an if statement, and then respond accordingly. Rather than repeating myself a million times, I thought it much easier just to write a post on the subject (DRY FTW!). Anyways, this type of code (pun intended) smacks of a duck type not being identified and utilised.

Imagine you have two classes. A parent and a child class. The child inheritance from the parent. Therefore the child should be able to do everything that a parent does and possibly more.

Last post we looked at dependencies and isolating them. This post we are going to work through some exercises.

Managing Dependencies