运行时不输出类下的代码

Question

我是班级和OOP的新手。当我通过终端运行此代码时，它不会显示任何内容，就像我按下Enter：

import types
import unittest


class FunctionValueOverride(object):
    def __init__(self, cls, default, override=None):
        self.cls = cls
        self.default = default
        self.override = override

    def __get__(self, obj, klass):
        if klass == self.cls:
            return self.override
        else:
            if obj:
                return types.MethodType(self.default, obj)
            else:
                return self.default


def fixture(cls):
    for t in vars(cls):
        if not callable(getattr(cls, t)) or t[:4] != "test":
            continue
        setattr(cls, t, FunctionValueOverride(cls, getattr(cls, t)))
    return cls


@fixture
class BaseTest(unittest.TestCase):
    def testCommon(self):
        print('Calling BaseTest:testCommon')
        value = 5
        self.assertEqual(value, 5)


class SubTest1(BaseTest):
    def testSub1(self):
        print('Calling SubTest1:testSub1')
        sub = 3
        self.assertEqual(sub, 3)


class SubTest2(BaseTest):

    def testSub2(self):
        print('Calling SubTest2:testSub2')
        sub = 4
        self.assertEqual(sub, 4)

if __name__ == '__main__':
    unittest.main()

我也试过在IDLE中运行它，结果相同。有人能帮助我吗？