Re: [aspectj-users] Testing Aspect Alone

["hai lin" <linhaiting@xxxxxxxxxxx>]

Hi Nick,

Thank you for your helpful advice. 

I've already had a good idea suggested by Eric Bodden in [aosd-discuss]. 
His suggestion is to add another "test" aspect with higher precedence to 
advice the advices themselves, and additionally to use  System.setOut() 
method to check the output stream. According to his suggestion, here I made 
a simple example to implement this kind of test:

//AspectToBeTested is the aspect to be tested
public aspect AspectToBeTested{
     public pointcut pc(): set(* TestCase.i)&&within(TestCase);
     before(): pc(){
         System.out.println("Data");          
     }
}

//class TestCase provides the context for testing import java.io.*;
public class TestCase{
     private int i;
     public static void main(String[] args){
          TestCase t=new TestCase();
          t.i=3;
     }
}

//SystemSetOutAspect is to redirect the output stream, with higher 
precedence 
//than AspectToBeTested 
import java.io.*;
public aspect SystemSetOutAspect{
   public static PrintStream TestCase.console;
   before(): set(* TestCase.i)&&within(TestCase){
          try{
            TestCase.console=System.out;
            PrintStream out= new PrintStream(new BufferedOutputStream(new 
FileOutputStream("setOut.txt")),true); 
            System.setOut(out);
          }catch(IOException e){}
   }
}

//ComparingResultAspect is to compare the output value with expected 
outcome, with  
//lower precedence than AspectToBeTested 
import java.io.*;
public aspect ComparingResultAspect{
   before(): set(* TestCase.i)&&within(TestCase){
      System.setOut(TestCase.console);
      try{
         BufferedReader br=new BufferedReader(new 
FileReader("setOut.txt"));
         String in="";
         while((in=br.readLine())!=null){
              if(in.equals("Private")){
                  System.out.println("Testing is successful.");
              }else{
                  System.out.println("Testing fails.");
              }
         }
      }catch(IOException e){}
   }
}

//PrecedenceAspect is to declare the precedence 
public aspect PrecedenceAspect{
   declare precedence: SystemSetOutAspect, AspectToBeTested, 
ComparingResultAspect;
}

The simple test program above is to test the before() advice with 
System.out.println(...) in itself. If this is not the best method to do 
this kind of test, any suggestion is welcomed.

By the way, you mentioned "a helper class", which I could not find in Java 
API documentation. Could you please explain in detail what it is used for? 
Thank you very much.

Adrian

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