How to mock a non static method of a class whose instance is passed as argument?

Question

How to mock a non static method of an argument class passed to a method? I'm testing below method:

public Seed getAppleSeed(AppleTree appleTree){
    Seed appleSeed = appleTree.getApple().getSeed();
    //Some logic flow
}

Rest of the classes are below:

public class AppleTree{
    public Apple getApple(){
        return new Apple():
    }
}

public class Apple{
    public Seed getSeed(){
        return new Seed():
    }
}

End goal is to test the flow of the getAppleSeed() method for which I need to mock the calls to getApple and getSeed.

Thanks

Answer 1

With mocking, like this:

AppleTree appleTree = Mockito.mock(AppleTree.class);
Apple apple = Mockito.mock(Apple.class);

Seed seed  = new Seed();

Mockito.when(appleTree.getApple()).thenReturn(apple);
Mockito.when(apple.getSeed()).thenReturn(seed);

Seed actual = getAppleSeed(appleTree);

assertThat(actual, is(seed));

Though if the actual code is as simple as what you have outlined in your question then I'd suggest that there is no need to mock Apple or AppleTree.