Tic-Tac-Toe game requirements

Tic-Tac-Toe is most often played by young children. The rules of the game are fairly simple.

Tic-Tac-Toe is a paper-and-pencil game for two players, X and O, who take turns marking the spaces in a 3×3 grid. The player who succeeds in placing three respective marks in a horizontal, vertical, or diagonal row, wins the game.

For more information about the game, please visit Wikipedia (http://en.wikipedia.org/wiki/Tic-tac-toe).

More detailed requirements will be presented later on.

The exercise consists of the creation of a single test that corresponds to one of the requirements. The test is followed by the code that fulfills the expectations of that test. Finally, if needed, the code is refactored. The same procedure should be repeated with more tests related to the same requirement. Once we're satisfied with tests and the implementation of...