public void Error_if_position_is_played()
{
var ticTacToe = new TicTacToeBoard();
ticTacToe.Change(2, "X");
Assert.Throws <ArgumentException>(() => ticTacToe.Change(2, "O"));
}
public void Place_symbols_in_correct_locations(int position, string player)
{
var ticTacToe = new TicTacToeBoard();
var board = ticTacToe.Change(position, player);
Assert.That(board[position - 1], Is.EqualTo(player));
}