How to mock a final class with mockito

Question

I have a final class, something like this:

public final class RainOnTrees{

   public void startRain(){

        // some code here
   }
}

I

Answer 1

I guess you made it final because you want to prevent other classes from extending RainOnTrees. As Effective Java suggests (item 15), there's another way to keep a class close for extension without making it final:

1. Remove the final keyword;

2. Make its constructor private. No class will be able to extend it because it won't be able to call the super constructor;

3. Create a static factory method to instantiate your class.

   // No more final keyword here.
   public class RainOnTrees {
   
       public static RainOnTrees newInstance() {
           return new RainOnTrees();
       }
   
   
       private RainOnTrees() {
           // Private constructor.
       }
   
       public void startRain() {
   
           // some code here
       }
   }
   

By using this strategy, you'll be able to use Mockito and keep your class closed for extension with little boilerplate code.