Rule

MockTest.java

import org.junit.Assert;
import org.junit.Rule;
import org.junit.Test;
import org.mockito.Mock;
import org.mockito.junit.MockitoJUnit;
import org.mockito.junit.MockitoRule;


import java.util.List;

import static org.mockito.ArgumentMatchers.anyInt;
import static org.mockito.Mockito.when;

public class MockTest {
    @Rule
    public MockitoRule rule = MockitoJUnit.rule();

    @Mock
    private List mockedList;

    @Test
    public void test1() {
        when(mockedList.get(anyInt()))
                .thenReturn(500);

        Object actual = mockedList.get(120);

        Assert.assertEquals(500, actual);
    }

}