def test_equals(self): self.assertEqual(next_bigger(12), 21)
def test_equals_2(self): self.assertEqual(next_bigger(513), 531)
def test_equals_7(self): self.assertEqual(next_bigger(1234567890), 1234567908)
def test_equals_6(self): self.assertEqual(next_bigger(531), -1)
def test_equals_5(self): self.assertEqual(next_bigger(111), -1)
def test_equals_4(self): self.assertEqual(next_bigger(9), -1)
def test_equals_3(self): self.assertEqual(next_bigger(2017), 2071)