c2addr := c2.LocalAddr().(*UDPAddr)
	if err != nil {
		t.Fatal(err)
	}
	defer c2.Close()

	n, err := c2.WriteToUDP([]byte("data"), c1addr)
	if err != nil {
		t.Fatal(err)
	}
	if n != 4 {
		t.Fatalf("got %d; want 4", n)
	}

	n, err = c1.WriteToUDP([]byte("data"), c2addr)
	if err != nil {
		t.Fatal(err)
	}
	if n != 4 {
		t.Fatalf("got %d; want 4", n)
	}

	c.SetWriteDeadline(time.Now().Add(someTimeout))
	c.SetReadBuffer(2048)
	c.SetWriteBuffer(2048)

	wb := []byte("UDPCONN TEST")
	rb := make([]byte, 128)
	if _, err := c.WriteToUDP(wb, c.LocalAddr().(*UDPAddr)); err != nil {
		t.Fatal(err)
	}
	if _, _, err := c.ReadFromUDP(rb); err != nil {
		t.Fatal(err)
	}
	if _, _, err := c.WriteMsgUDP(wb, nil, c.LocalAddr().(*UDPAddr)); err != nil {

	n, oobn, flags, addr, err = c.readMsg(b, oob)
	if err != nil {
		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return
}

// WriteToUDP acts like WriteTo but takes a UDPAddr.
func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.writeTo(b, addr)
	if err != nil {

		t.Fatal(err)
	}
	defer c.Close()

	ra, err := ResolveUDPAddr("udp", raddr)
	if err != nil {
		t.Fatal(err)
	}

	b := []byte("CONNECTED-MODE SOCKET")
	_, err = c.(*UDPConn).WriteToUDP(b, ra)
	if err == nil {
		t.Fatal("should fail")
	}
	if err != nil && err.(*OpError).Err != ErrWriteToConnected {
		t.Fatalf("should fail as ErrWriteToConnected: %v", err)
	}

		{"(*UDPConn).Write", Method, 0},
		{"(*UDPConn).WriteMsgUDP", Method, 1},
		{"(*UDPConn).WriteMsgUDPAddrPort", Method, 18},
		{"(*UDPConn).WriteTo", Method, 0},
		{"(*UDPConn).WriteToUDP", Method, 0},
		{"(*UDPConn).WriteToUDPAddrPort", Method, 18},
		{"(*UnixAddr).Network", Method, 0},
		{"(*UnixAddr).String", Method, 0},
		{"(*UnixConn).Close", Method, 0},
		{"(*UnixConn).CloseRead", Method, 1},

pkg net, method (*UDPConn) SetWriteDeadline(time.Time) error
pkg net, method (*UDPConn) Write([]uint8) (int, error)
pkg net, method (*UDPConn) WriteTo([]uint8, Addr) (int, error)
pkg net, method (*UDPConn) WriteToUDP([]uint8, *UDPAddr) (int, error)
pkg net, method (*UnixAddr) Network() string
pkg net, method (*UnixAddr) String() string
pkg net, method (*UnixConn) Close() error
pkg net, method (*UnixConn) File() (*os.File, error)