if got := out.String(); text != got {
			t.Errorf("want full output %q, got %q", text, got)
		}
	}
	wantErr = regexp.MustCompile("^no exit code")
	check("abc")
	check("exitcode")
	check("exitcode=")
	check("exitcode=123\n")
	wantErr = regexp.MustCompile("^bad exit code: .* value out of range")
	check("exitcode=999999999999999999999999")