Question asked on http://blog.codingtony.com/2011/02/mockito-recipes.html by Kalil Peixoto

MockitoExample.java

import static org.junit.Assert.*;
import static org.mockito.Matchers.*;
import static org.mockito.Mockito.*;

import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

	@Test
	public void testMockReturnArrayWithAnyList() {
		List<Something> returnList = new ArrayList<Something>();
		Something a = new Something();
		a.setReturnCode(1);;
		Something b = new Something();
		b.setReturnCode(2);;
		
		returnList.add(a);
		returnList.add(b);
		
		InterfaceToMock myMock = mock(InterfaceToMock.class);
		
		// here we have anyList in the expected call
		when(myMock.getList(anyList())).thenReturn(returnList);
	
		List<Something> test = myMock.getList(new ArrayList<Object>());
		assertEquals(returnList,test);
		assertEquals(test.get(0),a);
 
		test = myMock.getList(null);
		
        // When the parameter is null it returns an empty list.
		assertFalse(test.isEmpty());
		
	}
	
	@Test
	public void testMockReturnArrayWithNewArrayList() {
		List<Something> returnList = new ArrayList<Something>();
		Something a = new Something();
		a.setReturnCode(1);;
		Something b = new Something();
		b.setReturnCode(2);;
		
		returnList.add(a);
		returnList.add(b);
		
		InterfaceToMock myMock = mock(InterfaceToMock.class);
		
		// here we have new ArrayList<Object>() in the expected call
		when(myMock.getList(new ArrayList<Object>())).thenReturn(returnList);
	
		List<Something> test = myMock.getList(new ArrayList<Object>());
		assertEquals(returnList,test);
		assertEquals(test.get(0),a);
 
		test = myMock.getList(null);

		// When the parameter is null it returns an empty list.
		assertTrue(test.isEmpty());
		
	}
}