Final class and Final method - Mocking with Mockito 2

Is the feature provided by Mockito 2 to mock final methods and final classes using org.mockito.plugins.MockMaker(mock-maker-inline) generally available(released) or still in the incubation phase. I am using mockito-core-2.23.4 artifact in my application. Need suggestions in mocking the final classes and methods. Is it advisable to use this approach or look for alternate options?

As of Mockito 2.x, Mockito now supports mocking of final classes and methods.

Example:

Say we have a MyList class shown below as the collaborator in test cases.

We’ll add a new finalMethod to this class:

public class MyList extends AbstractList {
    final public int finalMethod() {
        return 0;
    }
}

And we'll also extend it with a final subclass:

public final class FinalList extends MyList {     
    @Override
    public int size() {
        return 1;
    }
}

Before Mockito can be used for mocking final classes and methods, it needs to be configured.

We need to add a text file to the project's src/test/resources/mockito-extensions directory named org.mockito.plugins.MockMaker and add a single line of text:

> mock-maker-inline

Mockito checks the extensions directory for configuration files when it is loaded. This file enables the mocking of final methods and classes.

Mock a Final Method:

Once Mockito is properly configured, a final method can be mocked like any other:

@Test
public void whenMockFinalMethodMockWorks() {
 
    MyList myList = new MyList();
 
    MyList mock = mock(MyList.class);
    when(mock.finalMethod()).thenReturn(1);
 
    assertNotEquals(mock.finalMethod(), myList.finalMethod());
}

By creating a concrete instance and a mock instance of MyList, we can compare the values returned by both versions of finalMethod() and verify that the mock is called.

Mock a Final Class:

Mocking a final class is just as easy as mocking any other class:

@Test
public void whenMockFinalClassMockWorks() {
 
    FinalList finalList = new FinalList();
 
    FinalList mock = mock(FinalList.class);
    when(mock.size()).thenReturn(2);
 
    assertNotEquals(mock.size(), finalList.size());
}

Similar to the test above, we create a concrete instance and a mock instance of our final class, mock a method and verify that the mocked instance behaves differently.

Reference: https://www.baeldung.com/mockito-final