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 {