testing: fix timing format inconsistency

Fixes #8175.

LGTM=r
R=golang-codereviews, r, gobot
CC=golang-codereviews
https://golang.org/cl/103320043

src/pkg/testing/example.go

@@ -71,7 +71,7 @@ func runExample(eg InternalExample) (ok bool) {
 
 	// Clean up in a deferred call so we can recover if the example panics.
 	defer func() {
-		d := time.Now().Sub(start)
+		dstr := fmtDuration(time.Now().Sub(start))
 
 		// Close pipe, restore stdout, get output.
 		w.Close()
@@ -84,10 +84,10 @@ func runExample(eg InternalExample) (ok bool) {
 			fail = fmt.Sprintf("got:\n%s\nwant:\n%s\n", g, e)
 		}
 		if fail != "" || err != nil {
-			fmt.Printf("--- FAIL: %s (%v)\n%s", eg.Name, d, fail)
+			fmt.Printf("--- FAIL: %s (%s)\n%s", eg.Name, dstr, fail)
 			ok = false
 		} else if *chatty {
-			fmt.Printf("--- PASS: %s (%v)\n", eg.Name, d)
+			fmt.Printf("--- PASS: %s (%s)\n", eg.Name, dstr)
 		}
 		if err != nil {
 			panic(err)

src/pkg/testing/testing.go

@@ -223,6 +223,11 @@ func decorate(s string) string {
 	return buf.String()
 }
 
+// fmtDuration returns a string representing d in the form "87.00s".
+func fmtDuration(d time.Duration) string {
+	return fmt.Sprintf("%.2fs", d.Seconds())
+}
+
 // TB is the interface common to T and B.
 type TB interface {
 	Error(args ...interface{})
@@ -446,15 +451,15 @@ func Main(matchString func(pat, str string) (bool, error), tests []InternalTest,
 }
 
 func (t *T) report() {
-	tstr := fmt.Sprintf("(%.2f seconds)", t.duration.Seconds())
-	format := "--- %s: %s %s\n%s"
+	dstr := fmtDuration(t.duration)
+	format := "--- %s: %s (%s)\n%s"
 	if t.Failed() {
-		fmt.Printf(format, "FAIL", t.name, tstr, t.output)
+		fmt.Printf(format, "FAIL", t.name, dstr, t.output)
 	} else if *chatty {
 		if t.Skipped() {
-			fmt.Printf(format, "SKIP", t.name, tstr, t.output)
+			fmt.Printf(format, "SKIP", t.name, dstr, t.output)
 		} else {
-			fmt.Printf(format, "PASS", t.name, tstr, t.output)
+			fmt.Printf(format, "PASS", t.name, dstr, t.output)
 		}
 	}
 }