Mocking final class with parameterized constructor

Question

I have a final class as below

public  class firstclass{

   private String firstmethod(){

       return new secondclass("params").somemethod();

}

}


public final class secondclass{

   secondclass(String params){

        //some code

}

public String somemethod(){

         // some code 
        return somevariable";
}
}

I have to here test first class so I have mocked this as below

secondclass classMock = PowerMockito.mock(secondclass .class);
        PowerMockito.whenNew(secondclass .class).withAnyArguments().thenReturn(classMock);
Mockito.doReturn("test").when(classMock).somemethod();

But it is not mocking as I expected can anyone help me?

Answer 1

1. The method firstclass.firstmethod() is private method. So try to test this method through public method in which it is getting called.

2. You can mock SecondClass and its final method using @RunWith(PowerMockRunner.class) and @PrepareForTest(SecondClass.class) annotations.

Please see below the working code:

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(SecondClass.class)
public class FirstClassTest{


    @Before
    public void init() {

    }

    @After
    public void clear() {

    }

    @Test
    public void testfirstmethod() throws Exception{

        SecondClass classMock = PowerMockito.mock(SecondClass.class);
        PowerMockito.whenNew(SecondClass.class).withAnyArguments().thenReturn(classMock);
        Mockito.doReturn("test").when(classMock).somemethod();

        new FirstClass().firstmethod();
    }
}

Libraries used: