TDD Spider Solitaire

Question

Another question about TDD from me. I have read some articles and book chapters about TDD and I understand why you should TDD and I understand the simple examples but it seems when I am trying this out in the real world I get stuck very easy.

Could you give me some simple TDD examples if you were to program the well known Spider Solitaire that comes with Windows Vista? Which tests would you start with?

Answer 1

Solitaire games involve cards.

So, you think of a Card class. You write some tests for individual Card objects. You write your Card class to pass the tests.

You need a deck that shuffles and deals into the layout. You think of the Deck class and the shuffle algorithm and how it maintains state for dealing. You write some tests for a Deck that shuffles and deals. You write your Deck class to pass the tests. [Note, this requires a mock random number generator that isn't actually random.]

Solitaire games involve a layout with empty spaces and cards. Some empty spaces of rules (Kings only or Aces only). Solitaire games sometimes involve a stock, more-or-less the remains of the Deck.

So you think of a Layout class with spaces for cards. You write some tests for the Layout and put in various Cards. You write your Layout class to pass the tests.

Then there's rules on what cards can be moved from the layout. Whole stacks, sub-stacks, top cards, whatever. You have an AllowedMove or GameState or some such class. Same drill. Define roughly what it does, write tests, finish the class.

You have user interface and display stuff. The drill is the same.

1. Rough out the class.

2. Define the tests.

3. Finish the class.

etc.

I cover this in detail in a book on OO Design.