def test_empty_cells_1(self):
b = Board()
b.grid = self.grid_1
empty_cells = b.empty_cells()
expected = {(0, 0), (1, 0), (1, 1), (2, 0), (2, 1), (3, 0), (3, 1), (3, 3)}
self.assertEqual(empty_cells, expected)
def test_empty_cells_0(self):
b = Board(self.seed)
empty_cells = b.empty_cells()
expected = {(i, j) for i in range(4) for j in range(4)}
expected.remove((2, 2))
self.assertEqual(empty_cells, expected)