Test-Driven Java Development, Second Edition - Second Edition

Refactoring

While the code that we have done so far fulfills the requirements set by the tests, it looks a bit confusing. If someone read it, it would not be clear as to what the play method does. We should refactor it by moving the code into separate methods. The refactored code will look like the following:

public void play(int x, int y) {
  checkAxis(x);
  checkAxis(y);
  setBox(x, y);
}

private void checkAxis(int axis) {
  if (axis < 1 || axis > 3) {
    throw new RuntimeException("X is outside board");
  }
}

private void setBox(int x, int y) {
  if (board[x - 1][y - 1] != '\0') {
    throw new RuntimeException("Box is occupied");
  } else {
    board[x - 1][y - 1] = 'X';
  }
}

With this refactoring, we did not change the functionality of the play method. It behaves ...