logJSON_test.go

type fataler interface {
       Fatal(...interface{})
}

func logJSON(t fataler, w io.Writer, label string, callback func() (interface{}, error)) {
       data, err := callback()
       if err != nil {
               t.Fatal(err, label)
       }

       enc := json.NewEncoder(w)
       enc.SetIndent("", "  ")
       enc.Encode(label)
       enc.Encode(data)
}

// logJSON(t, os.Stderr, "users", func() { return users, nil })