This document discusses test driven development (TDD) and using Mockito for testing. It provides an example of using TDD to develop a method that selects women and children from a list of persons. Tests are written using Mockito to mock dependencies like repositories before the production code is implemented. The document emphasizes that if the code is hard to test, then the design is likely flawed and recommends thinking about the test before writing the production code method.

1. www.luxoft.com
Test Driven Development
Using Mockito
By Andriy Slobodyanyk

2. www.luxoft.com
About me
Andriy Slobodyanyk
 Some years in Java Development
 Even TechLead of Luxoft team
 Bench press max 118 kg

3. www.luxoft.com
TDD

4. www.luxoft.com
TDD
 Tests
 Refactoring
 Documentation
 Design

5. www.luxoft.com
Interview Question
 There is a list of persons
 Select women and children from it

6. www.luxoft.com
Predicate
public List<Person> getVips(List<Person> persons) {
List<Person> result = new ArrayList<Person>();
for (Person p : persons) {
if (p.getGender() == FEMALE && p.getAge() > 16) {
result.add(p);
}
}
return result;
}

7. www.luxoft.com
TDD
If hard to write the test
then code design is bad

8. www.luxoft.com
Code “evolution”
@Service
public class PersonServiceImpl implements PersonService {
@Autowired
private UserRepository userRepository;
@Override
public void save(Person person) {
PersonEntity entity = new PersonEntity();
entity.setName(person.getName());
userRepository.save(entity);
}
}

9. www.luxoft.com
Code “evolution”
@Service
public class PersonServiceImpl implements PersonService {
@Autowired
private UserRepository userRepository;
@Autowired
private DeptRepository deptRepo;
@Override
public void save(Person person) {
PersonEntity entity = new PersonEntity();
entity.setName(person.getName());
DeptEntity dept = deptRepo.findBy(person.getDeptCode());
entity.setDept(dept);
userRepository.save(entity);
}
}

10. www.luxoft.com
Code “evolution”
@Service
public class PersonServiceImpl implements PersonService {
@Autowired
private UserRepository userRepository;
@Autowired
private DeptRepository deptRepo;
@Autowired
private MailService mailService;
@Override
public void save(Person person) {
PersonEntity entity = new PersonEntity();
entity.setName(person.getName());
DeptEntity dept = deptRepo.findBy(person.getDeptCode());
entity.setDept(dept);
if (Objects.equals(dept.getCountry(), "UA")) {
mailService.sendNotification(person.getName());
}
userRepository.save(entity);
}
}

11. www.luxoft.com
TDD
If hard to write the test
then code design is bad

12. www.luxoft.com
Interview Question
 There is a list of persons
 Select women and children from it

13. www.luxoft.com
Predicate
@Service
public class PersonServiceImpl implements PersonService {
public static Predicate<Person> VIP =
p -> p.getGender() == FEMALE || p.getAge() <= 16;
@Override
public List<Person> getVips(List<Person> persons) {
return persons.stream().filter(VIP).collect(toList());
}

14. www.luxoft.com
Predicate Test
public class PredicateTest {
@Test
public void test1() throws Exception {
Person person = new Person("Andriy", MALE, 33);
assertThat(PersonServiceImpl.VIP.test(person), is(false));
}
}

15. www.luxoft.com
Code “evolution”
@Service
public class PersonServiceImpl implements PersonService {
@Autowired
private UserRepository userRepository;
@Autowired
private DeptRepository deptRepo;
@Autowired
private MailService mailService;
@Override
public void save(Person person) {
PersonEntity entity = new PersonEntity();
entity.setName(person.getName());
entity.setAge(person.getAge());
DeptEntity dept = deptRepo.findBy(person.getDeptCode());
entity.setDept(dept);
if (Objects.equals(dept.getCountry(), "UA")) {
mailService.sendNotification(person.getName());
}
userRepository.save(entity);
}
}

16. www.luxoft.com
Writing test
public class PersonServiceTest {
@Test
public void testSave() throws Exception {
PersonService service = new PersonServiceImpl();
Person person = new Person("Andriy", MALE, 33, "UA");
service.save(person);
}
}

17. www.luxoft.com
Writing test
public class DeptRepositoryStub implements DeptRepository {
@Override
public DeptEntity findBy(Object countryCode) {
return new DeptEntity("UA");
}
}

18. www.luxoft.com
Writing test
public class MailServiceMock implements MailService {
private boolean invoked;
private String name;
@Override
public void sendNotification(String name) {
this.name = name;
invoked = true;
}
public boolean isInvoked() {
return invoked;
}
public String getName() {
return name;
}
}

19. www.luxoft.com
Writing test
public class PersonServiceTest {
@Test
public void testSave() throws Exception {
DeptRepository deptRepository = new DeptRepositoryStub();
UserRepository userRepository = new UserRepositoryMock();
MailServiceMock mailService = new MailServiceMock();
PersonService service = new PersonServiceImpl(userRepository, deptRepository, mailService);
Person person = new Person("Andriy", MALE, 33, "UA");
service.save(person);
assertThat(mailService.isInvoked(), is(true));
assertThat(mailService.getName(), equalTo("Andriy"));
}
}

20. www.luxoft.com
Mockito
@RunWith(MockitoJUnitRunner.class)
public class PersonServiceTest {
@InjectMocks
private PersonService service = new PersonServiceImpl();
@Mock
private DeptRepository deptRepository;
@Mock
private UserRepository userRepository;
@Mock
private MailService mailService;
@Test
public void testSave() throws Exception {
when(deptRepository.findBy(anyString()))
.thenReturn(new DeptEntity("UA"));
Person person = new Person("Andriy", MALE, 33, "UA");
service.save(person);
verify(mailService).sendNotification("Andriy");
ArgumentCaptor<PersonEntity> captor = forClass(PersonEntity.class);
verify(userRepository).save(captor.capture());
assertThat(captor.getValue().getAge(), equalTo(33));
}
}

21. www.luxoft.com
Mockito
@RunWith(MockitoJUnitRunner.class)
public class PersonServiceTest {
@InjectMocks
private PersonService service = new PersonServiceImpl();
@Mock
private DeptRepository deptRepository;
@Mock
private UserRepository userRepository;
@Mock
private MailService mailService;
}

22. www.luxoft.com
Mockito
@Test
public void testSave() throws Exception {
when(deptRepository.findBy(anyString()))
.thenReturn(new DeptEntity("UA"));
Person person = new Person("Andriy", MALE, 33, "UA");
service.save(person);
verify(mailService).sendNotification("Andriy");
ArgumentCaptor<PersonEntity> captor = forClass(PersonEntity.class);
verify(userRepository).save(captor.capture());
assertThat(captor.getValue().getAge(), equalTo(33));
}

23. www.luxoft.com
TDD
Think about the test / write it
Before coding the method

24. www.luxoft.com
THANK YOU