Test-Driven Java Development, Second Edition - Second Edition

Implementation

Now that we have a clear definition of when an exception should be thrown, the implementation should be straightforward:

package com.packtpublishing.tddjava.ch03tictactoe;

public class TicTacToe {
  public void play(int x, int y) {
    if (x < 1 || x > 3) {
      throw new RuntimeException("X is outside board");
    }
  }
}

As you can see, this code does not contain anything else, but the bare minimum required for the test to pass.

Some TDD practitioners tend to take minimum as a literal meaning. They would have the play method with only the throw new RuntimeException(); line. I tend to translate minimum to as little as possible within reason.

We're not adding numbers, nor are we returning anything. It's all about making small changes very fast. ...