How can stdout be captured or suppressed for Go(lang) testing?

Question

How can stdout be captured or suppressed for Go testing?

I am trying to teach myself go(lang) testing. In the code below, myshow.LoadPath prints lots of information to stdout (which is a normal side effect). It does however make for very noisy output when I run "go test" Is there a way to suppress or capture stdout?

For comparison, I'm thinking about something like this from the python world. http://pytest.org/latest/capture.html#captures

package slideshow_test

import (
    "os"
    "testing"

    "github.com/golliher/go-hpf/slideshow"
)

func setupTest() {
    myshow := slideshow.Slideshow{Name: "This is my show"}
    myshow.LoadPath("..")

}

func TestStub(t *testing.T) {
    if true == false {
        t.Fail()
    }
}

func TestMain(m *testing.M) {
    setupTest()
    os.Exit(m.Run())

}

Answer 1

os.Stdout which is used by the fmt.Printf and others is just a variable. So you can overwrite it at any time and restore it back when necessary. https://golang.org/pkg/os/#pkg-variables

Answer 2

To suppress the output during the test I use the following code. I fixes output as well as logging. After test is done it resets the output streams.

func TestStartStowWrongCommand(t *testing.T) {
 defer quiet()()   
 ...                      
}

func quiet() func() {
 null, _ := os.Open(os.DevNull)
 sout := os.Stdout
 serr := os.Stderr
 os.Stdout = null
 os.Stderr = null
 log.SetOutput(null)
 return func() {
  defer null.Close()
  os.Stdout = sout
  os.Stderr = serr
  log.SetOutput(os.Stderr)
 }
}