Unit Testing with JUnit & Mockito – Code Examples

Class Under Test

public CPResult createCard( Card card ) {

	CPResult cpResult = new CPResult();

	if( card != null ) {
		boolean validated = cdValidator.validate( card );
		if( validated ) {
			boolean cardCreated = cardDAO.createCard( card );
			if( !cardCreated ) {					
				cpResult.setMessage( CPResult.CARD_PERSISTENCE_FAILURE_MESSAGE );
			}
		} else {				
			cpResult.setMessage( CPResult.CARD_VALIDATION_FAILURE_MESSAGE );
		}
	} else {			
		cpResult.setMessage( CPResult.CARD_FATAL_ERROR_MESSAGE );
	}
	if( cpResult.getMessage() != null ) {
		cpResult.setStatus( CPResult.CARD_OPERATION_FAILURE );
	}
	return cpResult;		
}

Unit Test Class

public class PrepaidCardProcessorTest {

	private PrepaidCardProcessor prepaidCP;	
	@Mock private CardDetailsValidator cdValidator;
	@Mock private CardDAO cardDAO;

	@Before
	public void setUp() throws Exception {
		MockitoAnnotations.initMocks(this);
		prepaidCP = new PrepaidCardProcessor();
		prepaidCP.setCdValidator( cdValidator );
		prepaidCP.setCardDAO( cardDAO );
	}

	@After
	public void tearDown() throws Exception {
	}

	@Test
	public void cardIsNotCreatedIfMandatoryUserDetailsNotProvided() {
		// Create required objects for working with mocks and methods under test
		//
		Card card = new Card();		
		// Set the mock behavior on dependent objects
		//
		Mockito.when( cdValidator.validate( card ) ).thenReturn( false );
		// Execute the method under test 
		//
		CPResult cpresult = prepaidCP.createCard( card );
		// Perform assertions
		//
		assertTrue( cpresult.getStatus() == CPResult.CARD_OPERATION_FAILURE );
		assertTrue( cpresult.getMessage().equals( CPResult.CARD_VALIDATION_FAILURE_MESSAGE ) );
		// Verify the program execution path by checking on whether a method is invoked or not
		//
		Mockito.verify(cdValidator).validate(card);
		Mockito.verify(cardDAO, Mockito.never() ).createCard( card );
	}

	@Test
	public void cardIsNotCreatedIfCardFailedToPersistInDatabase() {
		// Create required objects for working with mocks and methods under test
		//
		Card card = new Card();		
		// Set the mock behavior on dependent objects
		//
		Mockito.when( cdValidator.validate( card ) ).thenReturn( true );
		Mockito.when( cardDAO.createCard( card ) ).thenReturn( false );
		// Execute the method under test 
		//
		CPResult cpresult = prepaidCP.createCard( card );
		// Perform assertions
		//
		assertTrue( cpresult.getStatus() == CPResult.CARD_OPERATION_FAILURE );
		assertTrue( cpresult.getMessage().equals( CPResult.CARD_PERSISTENCE_FAILURE_MESSAGE ) );
		// Verify the program execution path by checking on whether a method is invoked or not
		//
		Mockito.verify(cdValidator).validate(card);
		Mockito.verify(cardDAO ).createCard( card );
	}

	@Test
	public void cardIsCreatedIfAllBusinessRulesAreSatisfied() {
		// Create required objects for working with mocks and methods under test
		//
		Card card = new Card();		
		// Set the mock behavior on dependent objects
		//
		Mockito.when( cdValidator.validate( card ) ).thenReturn( true );
		Mockito.when( cardDAO.createCard( card ) ).thenReturn( true );
		// Execute the method under test 
		//
		CPResult cpresult = prepaidCP.createCard( card );
		// Perform assertions
		//
		assertTrue( cpresult.getStatus() == CPResult.CARD_OPERATION_SUCCESS );	
		assertNull( cpresult.getMessage() );
		// Verify the program execution path by checking on whether a method is invoked or not
		//
		Mockito.verify(cdValidator).validate(card);
		Mockito.verify(cardDAO ).createCard( card );
	}

}

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