don't spam Travis + valid dnstap payload

plugin/dnstap/dnstapio/io.go

@@ -3,6 +3,7 @@ package dnstapio
 import (
 	"fmt"
 	"io"
+	"os"
 
 	tap "github.com/dnstap/golang-dnstap"
 	"github.com/golang/protobuf/proto"
@@ -10,6 +11,7 @@ import (
 
 // DnstapIO wraps the dnstap I/O routine.
 type DnstapIO struct {
+	iolog  io.Writer
 	writer io.WriteCloser
 	queue  chan tap.Dnstap
 	stop   chan bool
@@ -25,7 +27,7 @@ type Protocol interface {
 
 // New dnstap I/O routine from Protocol.
 func New(w Protocol) *DnstapIO {
-	dio := DnstapIO{}
+	dio := DnstapIO{iolog: os.Stdout}
 	dio.writer = w
 	dio.queue = make(chan tap.Dnstap, 10)
 	dio.stop = make(chan bool)
@@ -38,7 +40,7 @@ func (dio *DnstapIO) Dnstap(payload tap.Dnstap) {
 	select {
 	case dio.queue <- payload:
 	default:
-		fmt.Println("[WARN] Dnstap payload dropped.")
+		fmt.Fprintln(dio.iolog, "[WARN] Dnstap payload dropped.")
 	}
 }
 
@@ -50,7 +52,7 @@ func (dio *DnstapIO) serve() {
 			if err == nil {
 				dio.writer.Write(frame)
 			} else {
-				fmt.Println("[ERROR] Invalid dnstap payload dropped.")
+				fmt.Fprintf(dio.iolog, "[ERROR] Invalid dnstap payload dropped: %s\n", err)
 			}
 		case <-dio.stop:
 			close(dio.queue)

plugin/dnstap/dnstapio/io_test.go

@@ -2,6 +2,7 @@ package dnstapio
 
 import (
 	"bytes"
+	"io/ioutil"
 	"sync"
 	"testing"
 	"time"
@@ -26,6 +27,7 @@ func (b buf) Close() error {
 func TestRace(t *testing.T) {
 	b := buf{&bytes.Buffer{}, 100 * time.Millisecond}
 	dio := New(b)
+	dio.iolog = ioutil.Discard // don't flood Travis
 	wg := &sync.WaitGroup{}
 	wg.Add(10)
 	for i := 0; i < 10; i++ {
@@ -38,7 +40,8 @@ func TestRace(t *testing.T) {
 					return
 				default:
 					time.Sleep(50 * time.Millisecond)
-					dio.Dnstap(tap.Dnstap{})
+					t := tap.Dnstap_MESSAGE
+					dio.Dnstap(tap.Dnstap{Type: &t})
 				}
 			}
 		}()