def test__str__(self):
     from sudoku_board import SudokuBox
     box = SudokuBox()
     box.add_answer(4)
     box.add_guess(4)
     box.add_guess(5)
     self.assertEqual(box.__str__(), '4')
 def test_add_answer(self):
     from sudoku_board import SudokuBox
     box = SudokuBox()
     box.add_answer(4)
     box.add_answer(5)
     self.assertEqual(box, SudokuBox(5))
     self.assertNotEqual(box, SudokuBox(4))
     with self.assertRaises(OverflowError):
         box.add_answer(10)
     with self.assertRaises(OverflowError):
         box.add_answer(0)
 def test_add_answer_preloaded_number(self):
     from sudoku_board import SudokuBox
     box = SudokuBox(1)
     self.assertFalse(box.add_answer(2))
     self.assertEqual(box, SudokuBox(1))
 def test_erase_answer(self):
     from sudoku_board import SudokuBox
     box = SudokuBox()
     box.add_answer(4)
     box.erase_answer()
     self.assertEqual(box.answer, 0)