public interface ProductDao { Product getProductById(int id); } ProductDao productDaoMock = Mockachino.mock(ProductDao.class); Mockachino.when(productDaoMock.getProductById(1)).thenReturn(new Product(1, "Mock Product")); ShoppingCart cart = new ShoppingCart(productDaoMock); cart.addProduct(1); Mockachino.verify(productDaoMock).getProductById(1);