07-1-B-Testing.adoc

Testing Backend Services

We implement a first unit test for testing the application service logic.

Preparations

1. Open the project and ensure that you add JUnit 5 and Mockito 2+ to the project dependencies in build.gradle:

   dependencies {
     // Add these lines to the dependency configuration, don't replace the existing dependencies
     	testImplementation "junit:junit:4.12"
     	testRuntime('org.junit.jupiter:junit-jupiter-engine:5.3.1')
       testImplementation('org.mockito:mockito-core:2.+')
     	testImplementation('org.mockito:mockito-junit-jupiter:2.18.3')
   }

   Note	Finding configuration settings for your Gradle/Maven project is very simple by searaching for them on MVNRepository: https://mvnrepository.com/

2. If you also would like to run your project from Eclipse, add an additional dependency:

   testImplementation group: 'org.junit.platform', name: 'junit-platform-launcher', version: "1.3.1"

3. Create a test class (in case you don’t already have one) EventregistrationServiceTests in the corresponding package under src/test/java:

   package ca.mcgill.ecse321.eventregistration;
   
   @RunWith(MockitoJUnitRunner.class)
   public class EventregistrationServiceTests {
   
   }

4. Build your project to ensure its dependencies are correctly loaded.

Writing tests

1. First, update/optimize the createPerson service method:

   @Transactional
   public Person createPerson(String name) {
     if (name == null || name == "") {
       throw new IllegalArgumentException("Person name cannot be empty!");
     }
     Person person = personRepository.findPersonByName(name);
     if ( person == null ) {
       person = new Person();
       person.setName(name);
       personRepositroy.save(person);
     }
     return person;
   }

2. Add the following imports to the test class:

   import org.junit.Before;
   import org.junit.Test;
   import org.junit.runner.RunWith;
   import org.mockito.InjectMocks;
   import org.mockito.Mock;
   import org.springframework.boot.test.context.SpringBootTest;
   import ca.mcgill.ecse321.eventregistration.dao.EventRepository;
   import ca.mcgill.ecse321.eventregistration.dao.PersonRepository;
   import ca.mcgill.ecse321.eventregistration.dao.RegistrationRepository;
   import ca.mcgill.ecse321.eventregistration.service.EventRegistrationService;
   import org.mockito.invocation.InvocationOnMock;
   import org.springframework.test.context.junit4.SpringRunner;
   import ca.mcgill.ecse321.eventregistration.controller.EventRegistrationRestController;
   import ca.mcgill.ecse321.eventregistration.model.Person;

3. Add the following static imports for methods:

   import static org.junit.Assert.assertEquals;
   import static org.junit.Assert.assertNotNull;
   import static org.mockito.ArgumentMatchers.anyString;
   import static org.mockito.Mockito.mock;
   import static org.mockito.Mockito.when;

4. Create the DAO mock for person

   @Mock
   private PersonRepository personDao;
   
   @InjectMocks
   private EventRegistrationService service;
   
   private static final String PERSON_KEY = "TestPerson";
   private static final String NONEXISTING_KEY = "NotAPerson";
   
   @Before
   public void setMockOutput() {
   	when(personDao.findPersonByName(anyString())).thenAnswer( (InvocationOnMock invocation) -> {
   		if(invocation.getArgument(0).equals(PERSON_KEY)) {
   			Person person = new Person();
   			person.setName(PERSON_KEY);
   			return person;
   		} else {
   			return null;
   		}
   	});
   }

5. Add test cases

   @Test
   public void testCreatePerson() {
   	assertEquals(0, service.getAllPersons().size());
   
   	String name = "Oscar";
   
   	try {
   		person = service.createPerson(name);
   	} catch (IllegalArgumentException e) {
   		// Check that no error occurred
   		fail();
   	}
   
   	assertEquals(name, person.getName());
   }
   
   @Test
   public void testCreatePersonNull() {
   	String name = null;
   	String error = null;
   
   	try {
   		person = service.createPerson(name);
   	} catch (IllegalArgumentException e) {
   		error = e.getMessage();
   	}
   
   	// check error
   	assertEquals("Person name cannot be empty!", error);
   }

6. Run the tests with gradle test from the command line in the root of the project, or in Eclipse, right click on the test class name then select Run As…​ > JUnit test.