How to override abstract base class behavior with Mockito

Question

I have code like this:

class Outer {
  private External external;
  class MyCallback extends ExternalAbstractCallback {
    void somethingHappened() { if (super.someCondition()) { ... }; }
  }

  public Outer() {
     external = ...;
  }

  public setExternal(External e) { external = e; } // test support

  public void doIt() {
    external.setCallback(new MyCallback());
    external.doSomething();
  }
}

I want to test the behavior of MyCallback when doIt() is called. I use Mockito to create a mock External and can then get external.doSomething() to execute the MyCallback.somethingHappened. Can I control the return value of the call to super.someCondtion at line 4? Can I rearrange the implementation to improve testability? The implementations of External and ExternalAbstractCallback cannot be changed.

score 3 · Answer 1 · answered Mar 26 '13 at 17:05

3

Your problem is that you can't mock new with Mockito. In a nutshell, code that you want to test should never call new.

Workarounds:

Add a getter/setter for the callback.
Move new MyCallback() into a new protected helper method which you override in your test

answered Mar 26 '13 at 17:05

Aaron Digulla

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+1 for the first sentence. But adding a getter/setter for MyCallback seems impossible, since MyCallback is an inner class. – kevin cline Mar 26 '13 at 17:37
What stops you from extracting the inner class? – Aaron Digulla Mar 27 '13 at 08:36
So? Make the things that you need to mutate [package private](http://stackoverflow.com/questions/215497/in-java-whats-the-difference-between-public-default-protected-and-private). – Aaron Digulla Mar 28 '13 at 11:42

How to override abstract base class behavior with Mockito

1 Answers1