package udp

import (
	"net"
	"testing"
)

// A "multicast" row whose group is not a multicast address.
//
// 127.0.0.1 in that box is the common mistake — it is the address every other
// field in every other program wants — and it used to fail the join on every
// interface with a Windows error about an address not being valid in its
// context. The row did not run and the message named nothing the operator had
// typed. Reported by an operator whose WSJT-X rows were dead for exactly this
// reason, while a third row on unicast worked perfectly beside them.
func TestOnlyRealMulticastGroupsAreJoined(t *testing.T) {
	for _, tc := range []struct {
		addr      string
		multicast bool
	}{
		{"224.0.0.1", true},   // the all-hosts group WSJT-X offers
		{"239.255.0.1", true}, // the administratively-scoped range
		{"127.0.0.1", false},  // loopback: the mistake
		{"192.168.1.10", false},
		{"0.0.0.0", false},
	} {
		ip := net.ParseIP(tc.addr)
		if ip == nil {
			t.Fatalf("%s does not parse", tc.addr)
		}
		if got := ip.IsMulticast(); got != tc.multicast {
			t.Errorf("%s: IsMulticast() = %v, wanted %v", tc.addr, got, tc.multicast)
		}
	}
}