TDD Demo - Bowling Game Kata

This repository forms part of the ONS Software Development Practices engineering training sessions. It contains a base project to run the bowling game kata from.

Branches

• master an empty project which can be used to practice/demonstrate the kata
• completed a branch with the completed code and a commit history detailing each step.

Bowling Game Kata

The bowling game kata is a well know code kata. The aim is to use TDD to implement a class which calculates the score of a 10 pin bowling game. The class should have the following interface:

class BowlingGame:
    def roll(self, pins):
        """
        Call this each time a ball is rolled passing in the number of pins that
        were knocked down.
        """

    def score(self):
        """
        Call this at the end of the game to get the final score.
        """

Rules of 10 Pin Bowling

• A game has 10 frames
• A player has 2 rolls per frame to try and knock down all 10 pins
• If a player knocks down all 10 pins in a frame then they score a spare:
  • The score for a spare is the 10 pins plus the next roll as a bonus
• If a player knocks down all 10 pins in the first roll of a frame then they score a strike:
  • If a strike is scored then there is no second roll in the frame
  • The score for a strike is the 10 pins plus the next 2 rolls as a bonus
  • If a strike is scored in the last frame then 2 bonus rolls are added to the frame
• A perfect game is 12 successive strikes and scores 300 points

Exceptions & Edge Cases

For a real implementation of this you would want to check for errors, including the following:

• Negative number of pins passed to roll
• More than 10 pins passed to roll
• Score called before the game is completed
• Roll called too many times

However, for this demonstration we are only focussing on the happy path.