1

I have method that I want to test. It's input parameter is a list of objects of a private static class

Class Invoker{

   public String method1(String inp){

   ArrayList<InnerClass> params = new ArrayList<>();
   params.add(new InnerClass("some value"));
   String op = method2(params);
   //other implementation
  }

   public String method2(ArrayList<InnerClass> list){

     //method implementation
  }

   private static class InnerClass {
      private String var1;

          public InnerClass(String str){
          super();
          this.str = str;
         }
   }
}

Now, I want to write a test case for method 'method1'. The issue I'm facing is that while testing, I'm not able to create the ArrayList in the test class.

Tejas Tasgaonkar
  • 167
  • 1
  • 8
  • method1 already creates this for you. You would only have this problem testing `method21 which should probably be private as InnerClass is. – Peter Lawrey Jun 25 '18 at 08:37
  • Possible duplicate of [Instantiate private inner class with java reflection](https://stackoverflow.com/questions/14112166/instantiate-private-inner-class-with-java-reflection) – Shloim Jun 25 '18 at 08:39
  • How are you going to call your public `method2` with a class that's not even visible to the caller? – daniu Jun 25 '18 at 08:43
  • @PeterLawrey I want to write inside the test case for method1 as: `when(spy.method2(list)).thenReturn("Some String"); ` So not able to create ArrayList list. To be clear I'm writing all test cases in another class – Tejas Tasgaonkar Jun 25 '18 at 09:18
  • If you feel it is valid to test this method this way, I suggest making the InnerClass package local and creating a test in that package. If you feel it should be private, perhaps it doesn't make sense to test it directly. – Peter Lawrey Jun 25 '18 at 09:24
  • @PeterLawrey Writing test cases for legacy code. Can't modify original class – Tejas Tasgaonkar Jun 25 '18 at 09:26
  • @TejasTasgaonkar in that case, I wouldn't test it in ways existing code cannot call it anyway. – Peter Lawrey Jun 25 '18 at 09:30
  • I appreciate the comeback! – GhostCat Nov 12 '18 at 07:29

1 Answers1

3

You are going down the wrong rabbit hole here.

Making an inner class private communicates to your readers (and the compiler btw) that this inner class in intended to only be used within the outer enclosing class. End of story.

Using the class name within the signature of a public method simply doesn't make sense therefore.

Of course, you could theoretically use reflection to work around this (until maybe Java 9 modules get into your way), but as said: doing so is a waste of time.

If you need to use things outside your class, don't make them private. So consider turning them package protected. Then users inside the same package have access, and so have unit tests that should live in the same package).

GhostCat
  • 137,827
  • 25
  • 176
  • 248
  • 1
    I'm writing test cases for some legacy code. No way to modify it now – Tejas Tasgaonkar Jun 25 '18 at 09:24
  • 1
    Then you could try the reflection thing. But what is the point of testing code when you aren't allowed to modify it in the first place. What will happen when you find a bug? You also can't use such tests as "vehicle" to later test a re-implementation - as anything using reflection is directly based on implementation details, so a re-implementation will break such tests easily. – GhostCat Jun 25 '18 at 09:26