code review 6973048: testing: only capture stdout when running examples

testing: only capture stdout when running examples

Fixes issue 4550.

[adg, 2012-12-19 22:46:37]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://code.google.com/p/go

[bradfitz, 2012-12-19 23:04:31]

LGTM

On Wed, Dec 19, 2012 at 2:46 PM, <adg@golang.org> wrote:

> Reviewers: golang-dev_googlegroups.com,
>
> Message:
> Hello golang-dev@googlegroups.com,
>
> I'd like you to review this change to
> https://code.google.com/p/go
>
>
> Description:
> testing: only capture stdout when running examples
>
> Fixes issue 4550.
>
> Please review this at
https://codereview.appspot.**com/6973048/<https://codereview.appspot.com/6973...
>
> Affected files:
>   M src/cmd/go/doc.go
>   M src/cmd/go/test.go
>   M src/pkg/testing/example.go
>
>
> Index: src/cmd/go/doc.go
> ==============================**==============================**=======
> --- a/src/cmd/go/doc.go
> +++ b/src/cmd/go/doc.go
> @@ -76,7 +76,13 @@
>                 do not delete it when exiting.
>         -x
>                 print the commands.
> +       -race
> +               enable data race detection.
> +               Currently supported only on linux/amd64,
> +               darwin/amd64 and windows/amd64.
>
> +       -ccflags 'arg list'
> +               arguments to pass on each 5c, 6c, or 8c compiler invocation
>         -compiler name
>                 name of compiler to use, as in runtime.Compiler (gccgo or
> gc)
>         -gccgoflags 'arg list'
> @@ -121,6 +127,7 @@
>         DIR(.exe)        from go build
>         DIR.test(.exe)   from go test -c
>         MAINFILE(.exe)   from go build MAINFILE.go
> +       *.so             from SWIG
>
>  In the list, DIR represents the final path element of the
>  directory, and MAINFILE is the base name of any Go source
> @@ -276,10 +283,10 @@
>     
code.google.com/p/goauth2/**oauth<http://code.google.com/p/goauth2/oauth>
>      code.google.com/p/sqlite
>
> -The -f flag specifies an alternate format for the list,
> -using the syntax of package template.  The default output
> -is equivalent to -f '{{.ImportPath}}'.  The struct
> -being passed to the template is:
> +The -f flag specifies an alternate format for the list, using the
> +syntax of package template.  The default output is equivalent to -f
> +'{{.ImportPath}}'.  One extra template function is available, "join",
> +which calls strings.Join. The struct being passed to the template is:
>
>      type Package struct {
>          Dir        string // directory containing package sources
> @@ -679,6 +686,9 @@
>             Run benchmarks matching the regular expression.
>             By default, no benchmarks run.
>
> +       -test.benchmem
> +           Print memory allocation statistics for benchmarks.
> +
>         -test.cpuprofile cpu.out
>             Write a CPU profile to the specified file before exiting.
>
> @@ -694,6 +704,18 @@
>             garbage collector, provided the test can run in the available
>             memory without garbage collection.
>
> +       -test.blockprofile block.out
> +           Write a goroutine blocking profile to the specified file
> +           when all tests are complete.
> +
> +       -test.blockprofilerate n
> +           Control the detail provided in goroutine blocking profiles by
> setting
> +           runtime.BlockProfileRate to n.  See 'godoc runtime
> BlockProfileRate'.
> +           The profiler aims to sample, on average, one blocking event
> every
> +           n nanoseconds the program spends blocked.  By default,
> +           if -test.blockprofile is set without this flag, all blocking
> events
> +           are recorded, equivalent to -test.blockprofilerate=1.
> +
>         -test.parallel n
>             Allow parallel execution of test functions that call
> t.Parallel.
>             The value of this flag is the maximum number of tests to run
> Index: src/cmd/go/test.go
> ==============================**==============================**=======
> --- a/src/cmd/go/test.go
> +++ b/src/cmd/go/test.go
> @@ -175,8 +175,8 @@
>
>         func BenchmarkXXX(b *testing.B) { ... }
>
> -An example function is similar to a test function but, instead of using
> *testing.T
> -to report success or failure, prints output to os.Stdout and os.Stderr.
> +An example function is similar to a test function but, instead of using
> +*testing.T to report success or failure, prints output to os.Stdout.
>  That output is compared against the function's "Output:" comment, which
>  must be the last comment in the function body (see example below). An
>  example with no such comment, or with no text after "Output:" is compiled
> Index: src/pkg/testing/example.go
> ==============================**==============================**=======
> --- a/src/pkg/testing/example.go
> +++ b/src/pkg/testing/example.go
> @@ -24,7 +24,7 @@
>
>         var eg InternalExample
>
> -       stdout, stderr := os.Stdout, os.Stderr
> +       stdout := os.Stdout
>
>         for _, eg = range examples {
>                 matched, err := matchString(*match, eg.Name)
> @@ -39,19 +39,19 @@
>                         fmt.Printf("=== RUN: %s\n", eg.Name)
>                 }
>
> -               // capture stdout and stderr
> +               // capture stdout
>                 r, w, err := os.Pipe()
>                 if err != nil {
>                         fmt.Fprintln(os.Stderr, err)
>                         os.Exit(1)
>                 }
> -               os.Stdout, os.Stderr = w, w
> +               os.Stdout = w
>                 outC := make(chan string)
>                 go func() {
>                         buf := new(bytes.Buffer)
>                         _, err := io.Copy(buf, r)
>                         if err != nil {
> -                               fmt.Fprintf(stderr, "testing: copying
> pipe: %v\n", err)
> +                               fmt.Fprintf(os.Stderr, "testing: copying
> pipe: %v\n", err)
>                                 os.Exit(1)
>                         }
>                         outC <- buf.String()
> @@ -62,9 +62,9 @@
>                 eg.F()
>                 dt := time.Now().Sub(t0)
>
> -               // close pipe, restore stdout/stderr, get output
> +               // close pipe, restore stdout, get output
>                 w.Close()
> -               os.Stdout, os.Stderr = stdout, stderr
> +               os.Stdout = stdout
>                 out := <-outC
>
>                 // report any errors
>
>
>

[adg, 2012-12-19 23:48:43]

*** Submitted as https://code.google.com/p/go/source/detail?r=1481cdef28a6 ***

testing: only capture stdout when running examples

Fixes issue 4550.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/6973048

[rsc, 2012-12-20 19:30:03]

thanks very much