MockitoTest.java

import org.junit.Before;
import org.junit.Test;

import static junit.framework.TestCase.assertEquals;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

public class MockitoTest {
    interface StringProvider {
        String getString();
    }

    private StringProvider provider;

    @Before
    public void setUp() {
        provider = mock(StringProvider.class);
    }

    @Test
    public void mokitoSample() {
        when(provider.getString()).thenReturn("mocked");
        String result = provider.getString();

        assertEquals("mocked", result);
        verify(provider).getString();
    }
}