def test_controlD(self):
        """
        A CTRL+D in the middle of a line doesn't close a connection,
        but at the beginning of a line it does.
        """
        self._testwrite(b"1 + 1")
        yield self.recvlineClient.expect(br"\+ 1")
        self._assertBuffer([b">>> 1 + 1"])

        self._testwrite(manhole.CTRL_D + b" + 1")
        yield self.recvlineClient.expect(br"\+ 1")
        self._assertBuffer([b">>> 1 + 1 + 1"])

        self._testwrite(b"\n")
        yield self.recvlineClient.expect(b"3\n>>> ")

        self._testwrite(manhole.CTRL_D)
        d = self.recvlineClient.onDisconnection
        yield self.assertFailure(d, error.ConnectionDone)

        A CTRL+D in the middle of a line doesn't close a connection,
        but at the beginning of a line it does.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_manhole.py