from __future__ import with_statement
from contextlib import *
import unittest

@contextmanager
def some_cm():
    raise ValueError('error from some_cm()')

@contextmanager
def other_cm():
    yield

class TestContextManager(unittest.TestCase):
    def test_a(self):
        with other_cm():
            try:
                with some_cm():
                    pass
            except:
                print 'catch'

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