refactor-for-testability (#3)

Co-authored-by: jdl <jdl@desktop>
Co-authored-by: jdl <jdl@crumpington.com>
Reviewed-on: #3

peer/packets-util_test.go

@@ -0,0 +1,76 @@
+package peer
+
+import (
+	"net/netip"
+	"reflect"
+	"testing"
+)
+
+func TestBinWriteRead_invalidAddrPort(t *testing.T) {
+	addr := netip.AddrPort{}
+	buf := make([]byte, 1024)
+	buf = newBinWriter(buf).
+		AddrPort(addr).
+		Build()
+
+	var addr2 netip.AddrPort
+	err := newBinReader(buf).
+		AddrPort(&addr2).
+		Error()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if addr2.IsValid() {
+		t.Fatal(addr, addr2)
+	}
+}
+
+func TestBinWriteRead(t *testing.T) {
+	buf := make([]byte, 1024)
+
+	type Item struct {
+		Type     byte
+		TraceID  uint64
+		Addrs    [8]netip.AddrPort
+		DestAddr netip.AddrPort
+	}
+
+	in := Item{
+		1,
+		2,
+		[8]netip.AddrPort{},
+		netip.AddrPortFrom(netip.AddrFrom4([4]byte{1, 2, 3, 4}), 22),
+	}
+
+	in.Addrs[0] = netip.AddrPortFrom(netip.AddrFrom4([4]byte{0, 1, 2, 3}), 20)
+	in.Addrs[2] = netip.AddrPortFrom(netip.AddrFrom4([4]byte{2, 3, 4, 5}), 22)
+	in.Addrs[3] = netip.AddrPortFrom(netip.AddrFrom4([4]byte{2, 3, 4, 3}), 23)
+	in.Addrs[4] = netip.AddrPortFrom(netip.AddrFrom4([4]byte{2, 3, 4, 4}), 24)
+	in.Addrs[5] = netip.AddrPortFrom(netip.AddrFrom4([4]byte{2, 3, 4, 5}), 25)
+	in.Addrs[6] = netip.AddrPortFrom(netip.AddrFrom4([4]byte{2, 3, 4, 6}), 26)
+	in.Addrs[7] = netip.AddrPortFrom(netip.AddrFrom4([4]byte{7, 8, 9, 7}), 27)
+
+	buf = newBinWriter(buf).
+		Byte(in.Type).
+		Uint64(in.TraceID).
+		AddrPort(in.DestAddr).
+		AddrPort8(in.Addrs).
+		Build()
+
+	out := Item{}
+
+	err := newBinReader(buf).
+		Byte(&out.Type).
+		Uint64(&out.TraceID).
+		AddrPort(&out.DestAddr).
+		AddrPort8(&out.Addrs).
+		Error()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !reflect.DeepEqual(in, out) {
+		t.Fatal(in, out)
+	}
+}