class BaseMixerTest(object):
    MIN = 0
    MAX = 100
    ACTUAL_MIN = MIN
    ACTUAL_MAX = MAX
    INITIAL = None

    mixer_class = None

    def setUp(self):
        assert self.mixer_class is not None, \
            "mixer_class must be set in subclass"
        # pylint: disable = E1102
        self.mixer = self.mixer_class(None)
        # pylint: enable = E1102

    def test_initial_volume(self):
        self.assertEqual(self.mixer.volume, self.INITIAL)

    def test_volume_set_to_min(self):
        self.mixer.volume = self.MIN
        self.assertEqual(self.mixer.volume, self.ACTUAL_MIN)

    def test_volume_set_to_max(self):
        self.mixer.volume = self.MAX
        self.assertEqual(self.mixer.volume, self.ACTUAL_MAX)

    def test_volume_set_to_below_min_results_in_min(self):
        self.mixer.volume = -10
        self.assertEqual(self.mixer.volume, self.ACTUAL_MIN)

    def test_volume_set_to_above_max_results_in_max(self):
        self.mixer.volume = self.MAX + 10
        self.assertEqual(self.mixer.volume, self.ACTUAL_MAX)

    def test_volume_is_not_float(self):
        self.mixer.volume = 1.0 / 3 * 100
        self.assertEqual(self.mixer.volume, 33)

class BaseMixerTest(object):
    MIN = 0
    MAX = 100
    ACTUAL_MIN = MIN
    ACTUAL_MAX = MAX
    INITIAL = None

    mixer_class = None

    def setUp(self):
        assert self.mixer_class is not None, \
            "mixer_class must be set in subclass"
        # pylint: disable = E1102
        self.mixer = self.mixer_class()
        # pylint: enable = E1102

    def test_initial_volume(self):
        self.assertEqual(self.mixer.volume, self.INITIAL)

    def test_volume_set_to_min(self):
        self.mixer.volume = self.MIN
        self.assertEqual(self.mixer.volume, self.ACTUAL_MIN)

    def test_volume_set_to_max(self):
        self.mixer.volume = self.MAX
        self.assertEqual(self.mixer.volume, self.ACTUAL_MAX)

    def test_volume_set_to_below_min_results_in_min(self):
        self.mixer.volume = -10
        self.assertEqual(self.mixer.volume, self.ACTUAL_MIN)

    def test_volume_set_to_above_max_results_in_max(self):
        self.mixer.volume = self.MAX + 10
        self.assertEqual(self.mixer.volume, self.ACTUAL_MAX)

    def test_volume_is_not_float(self):
        self.mixer.volume = 1.0 / 3 * 100
        self.assertEqual(self.mixer.volume, 33)

Fix mixer tests