testing: print test results to standard output

Errors in the code under test go to standard output.
Errors in testing or its usage go to standard error.

R=r
CC=golang-dev
https://golang.org/cl/5374090

src/pkg/testing/example.go

@@ -21,24 +21,23 @@ type InternalExample struct {
 func RunExamples(examples []InternalExample) (ok bool) {
 	ok = true
 
+	var eg InternalExample
+
 	stdout, stderr := os.Stdout, os.Stderr
 	defer func() {
 		os.Stdout, os.Stderr = stdout, stderr
 		if e := recover(); e != nil {
-			if err, ok := e.(error); ok {
-				fmt.Fprintln(os.Stderr, err)
-				os.Exit(1)
-			}
-			panic(e)
+			fmt.Printf("--- FAIL: %s\npanic: %v\n", eg.Name, e)
+			os.Exit(1)
 		}
 	}()
 
-	for _, eg := range examples {
+	for _, eg = range examples {
 		if *chatty {
-			fmt.Fprintln(os.Stderr, "=== RUN:", eg.Name)
+			fmt.Printf("=== RUN: %s\n", eg.Name)
 		}
 
-		// capture stdout and stderr for testing purposes
+		// capture stdout and stderr
 		r, w, err := os.Pipe()
 		if err != nil {
 			fmt.Fprintln(os.Stderr, err)
@@ -50,7 +49,7 @@ func RunExamples(examples []InternalExample) (ok bool) {
 			buf := new(bytes.Buffer)
 			_, err := io.Copy(buf, r)
 			if err != nil {
-				fmt.Fprintln(os.Stderr, err)
+				fmt.Fprintf(stderr, "testing: copying pipe: %v\n", err)
 				os.Exit(1)
 			}
 			outC <- buf.String()
@@ -67,16 +66,15 @@ func RunExamples(examples []InternalExample) (ok bool) {
 		out := <-outC
 
 		// report any errors
+		tstr := fmt.Sprintf("(%.2f seconds)", float64(ns)/1e9)
 		if out != eg.Output {
-			fmt.Fprintf(
-				os.Stderr,
-				"--- FAIL: %s\ngot:\n%s\nwant:\n%s\n",
-				eg.Name, out, eg.Output,
+			fmt.Printf(
+				"--- FAIL: %s %s\ngot:\n%s\nwant:\n%s\n",
+				eg.Name, tstr, out, eg.Output,
 			)
 			ok = false
 		} else if *chatty {
-			tstr := fmt.Sprintf("(%.2f seconds)", float64(ns)/1e9)
-			fmt.Fprintln(os.Stderr, "--- PASS:", eg.Name, tstr)
+			fmt.Printf("--- PASS: %s %s\n", eg.Name, tstr)
 		}
 	}