@Override
	public void testClean() {
		for (int i = 0; i < numberOfRows; i++)
			for (int j = 0; j < numberOfColumns; j++)
				assertEquals(null, board.get(i, j));

		for (int i = 0; i < numberOfRows; i++)
			for (int j = 0; j < numberOfColumns; j++)
				board.set(new Square(board, i, j), i, j);

		for (int i = 0; i < numberOfRows; i++)
			for (int j = 0; j < numberOfColumns; j++)
				assertNotNull(board.get(i, j));

		board.clean();

		for (int i = 0; i < numberOfRows; i++)
			for (int j = 0; j < numberOfColumns; j++)
				assertEquals(null, board.get(i, j));
	}