proposal: testing: add TB.SetStdout

[sivchari]

Proposal Details

I propose to add SetStdout to testing package.

If we want to test about Stdout, we must write like below.

func TestStdout(t *testing.T) {
	r, w, err := os.Pipe()
	if err != nil {
		t.Fatal(err)
	}

	defer r.Close()
	defer w.Close()

	oldStdout := os.Stdout

	t.Cleanup(func() {
		os.Stdout = oldStdout
	})

	os.Stdout = w

        // test
}

The reason I propose this API is similar with this.

Stdout is used globally and if we forget to restore the Stdout, many tests would be effected by this. So I think it's better approach to prevent it by to provide TB.SetStdout(). And there are a few codes that use this case in Go core. So I think it's common approach when we want to check stdout by go test.
As another idea, it might be good to check by static analysis.
Thanks.

[gabyhelp]

Related Issues and Documentation

• proposal: testing: add function to set output writer #59454

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[seankhliao]

see also #59928 testing.TB.Output()

[seankhliao]

Output() was accepted. I think in general it's best to avoid modifying stdout, and instead prefer to use explicit writers where necessary.