RED Need a result checker.
GREEN
RED Result checker needs to know the winning moves.
GREEN
RED Result checker needs to know the number of cells.
GREEN
RED Result checker needs to be able to check result (testing no result).
GREEN
REFACTOR Extracted number of cells as constructor parameter.
RED Check for a win.
GREEN
REFACTOR DRY ResultChecker test setup.
RED Test win for other player.
GREEN
REFACTOR Tidy up test names.
RED Test not-win because moves are spread across players.
GREEN
REFACTOR Extracted magic number into variable.
REFACTOR Extract helper method for getting current player.
REFACTOR Simplify current_player helper method.