Elegant?? Unit Testing (Droidcon Berlin 2016)

In this session we will learn the basics of Unit Testing and its importance. We will define what a Unit Test is, what type of Unit Tests there are and then talk about Test Doubles. Finally, we will focus on how to write new tests and improve existing ones by reviewing some Android Github projects.

Can you sleep soundly without writing tests? Really???

Transcript

1. ELEGANT?? UNIT TESTING by Pablo Guardiola @Guardiola31337
2. TWITTER @Guardiola31337 BLOG pguardiola.com/blog
3. 4 rules of simple design 1. Runs all the Tests
4. 4 rules of simple design 1. Runs all the Tests 2. Reveals all the intention
5. 4 rules of simple design 1. Runs all the Tests 2. Reveals all the intention 3. No duplication
6. 4 rules of simple design 1. Runs all the Tests 2. Reveals all the intention 3. No duplication 4. Fewest classes or methods
7. What do they all AGREE on?
8. PASSES its tests!
9. Have you ever asked yourself, WHY? What MOTIVATES you to write tests?
10. Testing motivators Validate the System
11. Testing motivators Validate the System Code Coverage
12. Testing motivators Validate the System Code Coverage Enable Refactoring
13. Testing motivators Validate the System Code Coverage Enable Refactoring Document the Behaviour of the System
14. Testing motivators Validate the System Code Coverage Enable Refactoring Document the Behaviour of the System Test Driven Development
15. Testing motivators Validate the System Code Coverage Enable Refactoring Document the Behaviour of the System Test Driven Development Customer Acceptance
16. Testing motivators Validate the System Code Coverage Enable Refactoring Document the Behaviour of the System Test Driven Development Customer Acceptance …
17. Styles of Testing STATE VERIFICATION
18. Styles of Testing STATE VERIFICATION BEHAVIOR VERIFICATION
19. HYBRID
20. Unit Test SOLITARY 1. Never crosses boundaries
21. Unit Test SOLITARY 1. Never crosses boundaries 2.The Class Under Test should be the only concrete class found in a test
22. Unit Test SOLITARY SOCIABLE 1. Never crosses boundaries 2.The Class Under Test should be the only concrete class found in a test
23. FIRST FAST
24. FIRST FAST INDEPENDENT
25. FIRST FAST INDEPENDENT REPEATABLE
26. FIRST FAST INDEPENDENT REPEATABLE SELF-VALIDATING
27. FIRST FAST INDEPENDENT REPEATABLE SELF-VALIDATING TIMELY
28. Test Doubles DUMMY
29. Dummy public class DummyAuthorizer implements Authorizer {
 @Override
 public Boolean authorize(String username, String password) {
 return null;
 }
 }
30. Test Doubles DUMMY STUB
31. Stub public class AcceptingAuthorizerStub implements Authorizer {
 @Override
 public Boolean authorize(String username, String password) {
 return true;
 }
 }
32. Test Doubles DUMMY STUB SPY
33. Spy public class AcceptingAuthorizerSpy implements Authorizer {
 public boolean authorizeWasCalled = false;
 
 public Boolean authorize(String username, String password) {
 authorizeWasCalled = true;
 return true;
 }
 }
34. Test Doubles DUMMY STUB SPY MOCK
35. Mock public class AcceptingAuthorizerVerificationMock implements Authorizer {
 public boolean authorizeWasCalled = false;
 
 public Boolean authorize(String username, String password) {
 authorizeWasCalled = true;
 return true;
 }
 
 public boolean verify() {
 return authorizeWasCalled;
 }
 }
36. Test Doubles DUMMY STUB SPY MOCK FAKE
37. Fake public class AcceptingAuthorizerFake implements Authorizer {
 public Boolean authorize(String username, String password) {
 return username.equals("Bob");
 }
 }
38. AAA ARRANGE
39. AAA ARRANGE ACT
40. AAA ARRANGE ACT ASSERT
41. What about ANDROID?
42. ANDROID Unit Testing Java Module
43. ANDROID Unit Testing Java Module AS 1.1 + Android Gradle Plugin
44. ANDROID Unit Testing Java Module MVP AS 1.1 + Android Gradle Plugin
45. ANDROID Unit Testing Java Module MVP AS 1.1 + Android Gradle Plugin MVVM
46. ANDROID Unit Testing Java Module MVP CLEAN Architecture AS 1.1 + Android Gradle Plugin MVVM
47. ANDROID Unit Testing Java Module MVP CLEAN Architecture AS 1.1 + Android Gradle Plugin MVVM Catan Architecture
48. ANDROID Unit Testing Java Module Mosby MVP CLEAN Architecture AS 1.1 + Android Gradle Plugin MVVM Catan Architecture
49. ANDROID Unit Testing Java Module Rosie Mosby MVP CLEAN Architecture AS 1.1 + Android Gradle Plugin MVVM Catan Architecture
50. ANDROID Unit Testing … Java Module Rosie Mosby MVP CLEAN Architecture AS 1.1 + Android Gradle Plugin MVVM Catan Architecture
51. DECOUPLED Architecture
52. Where do I START?
53. public class FooTest {
 
 @Test
 public void sampleTest() throws Exception {
 assertEquals(expected, actual);
 }
 } JUnit
54. Clean Contacts @Test public void obtainContactFirstNameFromRepo() throws Exception {
 ContactsBddDataSource mockContactsBddDataSource = mock(ContactsBddDataSource.class);
 ContactsNetworkDataSource mockContactsNetworkDataSource = mock(ContactsNetworkDataSource.class);
 ContactsRepositoryImp contactsRepository =
 new ContactsRepositoryImp(mockContactsNetworkDataSource, mockContactsBddDataSource);
 Contact droidCon = new Contact();
 Name name = new Name();
 name.setFirst("droidcon Berlin");
 droidCon.setName(name);
 when(mockContactsBddDataSource.obtain(“droidcon MD5")).thenReturn(droidCon);
 
 Contact contact = contactsRepository.obtain("droidcon MD5");
 
 assertEquals("droidcon Berlin", contact.getName().getFirst());
 }
55. Clean Contacts @Test public void contactsInteractorExecutedWhenResumed() throws Exception {
 InteractorInvoker interactorInvoker = mock(InteractorInvoker.class);
 GetContactsInteractor getContactsInteractor = mock(GetContactsInteractor.class);
 final ListMapper<Contact, PresentationContact> listMapper = mock(ListMapper.class);
 ThreadSpec mainThreadSpec = mock(ThreadSpec.class);
 MainPresenter mainPresenter =
 new MainPresenter(interactorInvoker, getContactsInteractor, listMapper, mainThreadSpec);
 
 mainPresenter.onResume();
 
 verify(interactorInvoker).execute(Mockito.eq(getContactsInteractor), Mockito.any(InteractorOutputImp.class));
 }
56. How do I IMPROVE my tests? DAMP
57. One Assertion Per Test (State Verification) @Test public void shouldCreateVerboseTraceFromStringTrace() throws Exception {
 Trace trace = Trace.fromString(VERBOSE_TRACE);
 
 assertEquals(TraceLevel.VERBOSE, trace.getLevel());
 assertEquals(ANY_TRACE_DATE + " " + VERBOSE_TRACE_MESSAGE, trace.getMessage());
 }
58. It’s ANNOYING to have to look at the STACKTRACE to know what’s FAILING
59. It’s ANNOYING to have to look at the STACKTRACE to know what’s FAILING Have NO INFORMATION about REMAINING TESTS
60. One Assertion Per Test (Behavior Verification) @Test public void shouldNotUpdateFilterIfPresenterIsNotInitialized() {
 presenter.updateFilter(ANY_FILTER);
 
 verify(lynx, never()).setConfig(any(LynxConfig.class));
 verify(lynx, never()).restart();
 }
61. Expect Literals @Test
 public void testSaveAllNextLevel() throws Exception {
 doReturn(Boolean.TRUE).when(repository).hasNextLevel();
 
 assertEquals(elements.size(), repository.saveAll(elements).size());
 verify(nextLevel, times(1)).saveAll(anyCollection());
 }
62. Expect Literals @Test
 public void testSaveAllNextLevel() throws Exception {
 doReturn(Boolean.TRUE).when(repository).hasNextLevel();
 
 assertEquals(3, repository.saveAll(elements).size());
 verify(nextLevel, times(1)).saveAll(anyCollection());
 }
63. READABILITY LITERALS will REFLECT the examples from the BUSINESS
64. Value Objects vs Expect Literals CONVERT VALUE OBJECT into a LITERAL
65. Avoid Inline Setup @Before
 public void setUp() throws Exception {
 initMocks(this);
 
 elements.add(mockedElement1);
 elements.add(mockedElement2);
 elements.add(mockedElement3);
 
 ids.add(EXPECTED_FIRST_ID);
 ids.add(EXPECTED_SECOND_ID);
 ids.add(EXPECTED_THIRD_ID);
 
 repository = new BaseFastRepositoryImpl(currentLevel, null);
 }
66. READABILITY Avoid CODE DUPLICATION? BUILDERS
67. Questionable Tests Testing Language Features or Standard Library Classes
68. Questionable Tests Testing Language Features or Standard Library Classes Testing Framework Features or Classes
69. Don’t test your stubs @Test
 public void doNotTestYourStubs() throws Exception {
 Name name = mock(Name.class);
 // blah blah blah...
 when(name.getFullName()).thenReturn("Don't test your stubs, please!");
 // 27 lines of stuff...
 assertEquals("Don't test your stubs, please!", name.getFullName());
 }
70. Should we even bother writing Unit Tests? “The key is to test the areas that you are most worried about going wrong. That way you get the most benefit for your testing effort.” Martin Fowler, Refactoring
71. “Practise makes perfect.”
72. Thank you! @Guardiola31337 pguardiola.com guardiola31337@gmail.com
73. Extreme Programming Explained: Embrace Change, Kent Beck, AddisonWesley. Working Effectively with Unit Tests by Jay Fields Bibliography Mocks Aren’t Stubs (www.martinfowler.com/articles/mocksArentStubs.html) The Little Mocker (blog.8thlight.com/uncle-bob/2014/05/14/TheLittleMocker.html) https://github.com/PaNaVTEC/Clean-Contacts https://github.com/pedrovgs/Lynx https://github.com/Guardiola31337/CatanArchitecture Ted Mosby - Software Architect (http://hannesdorfmann.com/android/mosby) Responsible Design for Android by J. B. Rainsberger Clean Code: A handbook of Agile Software Craftsmanship, Robert C. Martin Software Craftsmanship by Sandro Mancuso