//pretty print
 public void Print(PrettyPrinter printer)
 {
     printer.Println("TestResult (");
     using (printer.IndentCookie()) {
         printer.Print("testId = "); TestId.PrintEx(printer); printer.Println();
         printer.Print("output = "); Output.PrintEx(printer); printer.Println();
         printer.Print("duration = "); Duration.PrintEx(printer); printer.Println();
         printer.Print("status = "); Status.PrintEx(printer); printer.Println();
     }
     printer.Print(")");
 }