wgengine/packet: add some tests, more docs, minor Go style, performance changes

wgengine/packet/packet_test.go

@@ -0,0 +1,49 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"net"
+	"testing"
+)
+
+func TestIPString(t *testing.T) {
+	const str = "1.2.3.4"
+	ip := NewIP(net.ParseIP(str))
+
+	var got string
+	allocs := testing.AllocsPerRun(1000, func() {
+		got = ip.String()
+	})
+
+	if got != str {
+		t.Errorf("got %q; want %q", got, str)
+	}
+	if allocs != 1 {
+		t.Errorf("allocs = %v; want 1", allocs)
+	}
+}
+
+func TestQDecodeString(t *testing.T) {
+	q := QDecode{
+		IPProto: TCP,
+		SrcIP:   NewIP(net.ParseIP("1.2.3.4")),
+		SrcPort: 123,
+		DstIP:   NewIP(net.ParseIP("5.6.7.8")),
+		DstPort: 567,
+	}
+	got := q.String()
+	want := "TCP{1.2.3.4:123 > 5.6.7.8:567}"
+	if got != want {
+		t.Errorf("got %q; want %q", got, want)
+	}
+
+	allocs := testing.AllocsPerRun(1000, func() {
+		got = q.String()
+	})
+	if allocs != 1 {
+		t.Errorf("allocs = %v; want 1", allocs)
+	}
+}