import static org.easymock.EasyMock.*; public interface DataService { public String fetchData(); } public class DataProcessorTest { public void testProcessData() { DataService mockDataService = mock(DataService.class); expect(mockDataService.fetchData()).andReturn("Mock Data"); replay(mockDataService); DataProcessor dataProcessor = new DataProcessor(); dataProcessor.setDataService(mockDataService); String result = dataProcessor.processData(); verify(mockDataService); assertEquals("Processed Mock Data", result); } }