'L{PIDFile.read} re-raises L{OSError} if the associated C{errno} is
anything other than L{errno.ENOENT}.'

def test_readOpenRaisesOSErrorNotENOENT(self):

    def oops(mode='r'):
        raise OSError(errno.EIO, 'I/O    error')
    self.patch(DummyFilePath, 'open', oops)
    pidFile = PIDFile(DummyFilePath())
    error = self.assertRaises(OSError, pidFile.read)
    self.assertEqual(error.errno, errno.EIO)
