import unittest
import weakref

class TestCase(unittest.TestCase):

    def test_traceback_freed(self):
        ref = [None]
        class A: pass
        class Foo(unittest.TestCase):
            def foo(self):
                a = A()
                ref[0] = weakref.ref(a)
                try:
                    raise IOError
                except IOError:
                    raise ValueError
            def test(self):
                self.assertRaises(ValueError, self.foo)

        Foo("test").run()
        self.assertIsNone(ref[0]())

def test_main():
    unittest.main()

if __name__ == '__main__':
    test_main()