def test_setNonBlocking(self):
        """
        L{fdesc.setNonBlocking} sets a file description to non-blocking.
        """
        r, w = os.pipe()
        self.addCleanup(os.close, r)
        self.addCleanup(os.close, w)
        self.assertFalse(fcntl.fcntl(r, fcntl.F_GETFL) & os.O_NONBLOCK)
        fdesc.setNonBlocking(r)
        self.assertTrue(fcntl.fcntl(r, fcntl.F_GETFL) & os.O_NONBLOCK)

        L{fdesc.setNonBlocking} sets a file description to non-blocking.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_fdesc.py