@@ -4,12 +4,40 @@ import (

 	"bytes"

 	"encoding/json"

 	"io/ioutil"

+	"regexp"

+	"strings"

 	"testing"

 	"time"

 	"github.com/docker/docker/pkg/timeutils"

 )

+func TestWriteLog(t *testing.T) {

+	var buf bytes.Buffer

+	e := json.NewEncoder(&buf)

+	testLine := "Line that thinks that it is log line from docker\n"

+	for i := 0; i < 30; i++ {

+		e.Encode(JSONLog{Log: testLine, Stream: "stdout", Created: time.Now()})

+	}

+	w := bytes.NewBuffer(nil)

+	format := timeutils.RFC3339NanoFixed

+	if err := WriteLog(&buf, w, format); err != nil {

+		t.Fatal(err)

+	}

+	res := w.String()

+	t.Logf("Result of WriteLog: %q", res)

+	lines := strings.Split(strings.TrimSpace(res), "\n")

+	if len(lines) != 30 {

+		t.Fatalf("Must be 30 lines but got %d", len(lines))

+	}

+	logRe := regexp.MustCompile(`\[.*\] Line that thinks that it is log line from docker`)

+	for _, l := range lines {

+		if !logRe.MatchString(l) {

+			t.Fatalf("Log line not in expected format: %q", l)

+		}

+	}

+}

+

 func BenchmarkWriteLog(b *testing.B) {

 	var buf bytes.Buffer

 	e := json.NewEncoder(&buf)