'The file descriptor passed to L{installHandler} has a byte written to
it when SIGCHLD is delivered to the process.'

def test_installHandler(self):

    (read, write) = self.pipe()
    installHandler(write)
    exc = self.assertRaises(OSError, os.read, read, 1)
    self.assertEqual(exc.errno, errno.EAGAIN)
    os.kill(os.getpid(), signal.SIGCHLD)
    self.assertEqual(len(os.read(read, 5)), 1)
