'Ensure that if tell gives an IOError super_len doesn\'t fail'

@pytest.mark.parametrize('error', [IOError, OSError])
def test_super_len_tell_ioerror(self, error):

    class NoLenBoomFile(object, ):
        def tell(self):
            raise error()
        def seek(self, offset, whence):
            pass
    assert (super_len(NoLenBoomFile()) == 0)
