Easier way to dnstap? (#1496)

* Easier way to dnstap?

* Remove unnecessary function parameter from Tapper

* golint

* golint 2

* Proxy dnstap tests

* README.md & doc

* net.IP

* Proxy test was incorrect

* Small changes

* Update README.md

* Was not reporting dnstap errors + test

* Wasn't working at all, now it's ok

* Thanks Travis

plugin/dnstap/taprw/writer_test.go

@@ -1,41 +1,14 @@
 package taprw
 
 import (
-	"errors"
 	"testing"
 
-	"github.com/coredns/coredns/plugin/dnstap/msg"
 	"github.com/coredns/coredns/plugin/dnstap/test"
 	mwtest "github.com/coredns/coredns/plugin/test"
 
-	tap "github.com/dnstap/golang-dnstap"
 	"github.com/miekg/dns"
 )
 
-type TapFailer struct {
-}
-
-func (TapFailer) TapMessage(*tap.Message) error {
-	return errors.New("failed")
-}
-func (TapFailer) TapBuilder() msg.Builder {
-	return msg.Builder{Full: true}
-}
-
-func TestDnstapError(t *testing.T) {
-	rw := ResponseWriter{
-		Query:          new(dns.Msg),
-		ResponseWriter: &mwtest.ResponseWriter{},
-		Tapper:         TapFailer{},
-	}
-	if err := rw.WriteMsg(new(dns.Msg)); err != nil {
-		t.Errorf("dnstap error during Write: %s", err)
-	}
-	if rw.DnstapError() == nil {
-		t.Fatal("no dnstap error")
-	}
-}
-
 func testingMsg() (m *dns.Msg) {
 	m = new(dns.Msg)
 	m.SetQuestion("example.com.", dns.TypeA)
@@ -69,12 +42,18 @@ func TestClientQueryResponse(t *testing.T) {
 		t.Fatalf("%d msg trapped", l)
 		return
 	}
-	want := d.ToClientQuery()
+	want, err := d.ToClientQuery()
+	if err != nil {
+		t.Fatal("Testing data must build", err)
+	}
 	have := trapper.Trap[0]
 	if !test.MsgEqual(want, have) {
 		t.Fatalf("query: want: %v\nhave: %v", want, have)
 	}
-	want = d.ToClientResponse()
+	want, err = d.ToClientResponse()
+	if err != nil {
+		t.Fatal("Testing data must build", err)
+	}
 	have = trapper.Trap[1]
 	if !test.MsgEqual(want, have) {
 		t.Fatalf("response: want: %v\nhave: %v", want, have)