Spring Framework

In my previous post, I showed you how to create a HomeController for our home page in your application. You might have noted that there was little code that linked your HomeController with Spring that was included. It is simply a plain old java object (POJO). In this tip, we will look at unit testing your controller. Unit testing your controller will be very easy since a POJO doesn’t need you to mock any Spring or other specific objects. I will create a test object using standard naming conventions, XXXTest, in order to do this. In the case of our home controller, it will be HomeControllerTest.

Java Code:

import static com.acme.springwebapp.web.HomeController.*;
import static java.util.Arrays.*;
import static org.junit.Assert.*;
import static org.mockito.Mockito.*;

import java.util.HashMap;
import java.util.List;

import org.testng.annotations.Test;

import com.acme.springwebapp.domain.Car;
import com.acme.springwebapp.service.CarService;

public class HomeControllerTest {

	@Test
	public void shouldDisplayRecentCars() {
		List<Car> expectedCars = asList(new Car(), 
				new Car(), new Car());
		CarService carService = mock(CarService.class);
		when(carService.getCars(DEFAULT_CARS_PER_PAGE))
				.thenReturn(expectedCars);
		
		HomeController controller = new HomeController(carService);
		HashMap<String, Object> model = new HashMap<String, Object>();
		String viewName = controller.showHomePage(model);
		assertEquals("home", viewName);
		assertSame(expectedCars, model.get("cars"));
		verify(carService).getCars(DEFAULT_CARS_PER_PAGE);
	}
}

First note that I have used Google’s open source Mockito mock framework in order to provide a mock implementation of CarService. With the mock CarService I just create a new instance of HomeController and then call the showHomePage() method. I then assert the car list returned from the mock CarService in the model Map under the cars key. This method returns a logical view name of home.