middleware/chaos: fix version (#669)

* middleware/chaos: fix version

Move the version setting into a init function so it is done early. Then
tweak the setup code for chaos a bit to correctly pick this version up.
Add an integration test to pick this up in the toplevel test/ directory.

Fixes #667

* Update tests

test/chaos_test.go

@@ -0,0 +1,48 @@
+package test
+
+import (
+	"io/ioutil"
+	"log"
+	"testing"
+
+	// Plug in CoreDNS, needed for AppVersion and AppName in this test.
+	_ "github.com/coredns/coredns/coremain"
+
+	"github.com/mholt/caddy"
+	"github.com/miekg/dns"
+)
+
+func TestChaos(t *testing.T) {
+	corefile := `.:0 {
+		chaos
+}
+`
+
+	i, err := CoreDNSServer(corefile)
+	if err != nil {
+		t.Fatalf("Could not get CoreDNS serving instance: %s", err)
+	}
+	// Stop the server.
+	defer i.Stop()
+
+	udp, _ := CoreDNSServerPorts(i, 0)
+	if udp == "" {
+		t.Fatalf("Could not get UDP listening port")
+	}
+
+	log.SetOutput(ioutil.Discard)
+
+	m := new(dns.Msg)
+	m.SetQuestion("version.bind.", dns.TypeTXT)
+	m.Question[0].Qclass = dns.ClassCHAOS
+
+	resp, err := dns.Exchange(m, udp)
+	if err != nil {
+		t.Fatalf("Expected to receive reply, but didn't: %v", err)
+	}
+	chTxt := resp.Answer[0].(*dns.TXT).Txt[0]
+	version := caddy.AppName + "-" + caddy.AppVersion
+	if chTxt != version {
+		t.Fatalf("Expected version to bo %s, got %s", version, chTxt)
+	}
+}