Testing made sweet with a Mockito

Slides from my talk at Devoxx Belgium 2016
video: https://www.youtube.com/shared?ci=gkLiuk-z61A

Thanks to many tools and libraries, writing unit tests is a breeze! So all your apps currently have >80% code coverage, right? Yay! Or wait... is it really? Is all your common logic (networking, databases,...) tested? Do you isolate parts of your code base to keep your tests small? And what about providing relevant testing data?

In order to achieve this, you need to make use of mocks and stubs. And that's exactly what this talk will be about: What is a mock? What's the difference between a mock and a stub? Are mocks the only way to provide relevant data for your unit tests? What do I do with final classes/methods in the SDKs I use? How do I architect my app to make it easier to test? ...

After having adopted TDD as my main development workflow for almost a year now, I feel comfortable saying everything can be tested. Its just a matter of having someone experience show you how.

Transcript

1. @MOLSJEROEN
   #DEVOXX #MOCKITO
   TESTING MADE SWEET
   WITH A MOCKITO
   #DEVOXX #MOCKITO
   

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2. @MOLSJEROEN
   #DEVOXX #MOCKITO
   

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3. @MOLSJEROEN
   #DEVOXX #MOCKITO
   IF YOU DON’T LIKE UNIT TESTING YOUR
   PRODUCT, MOST LIKELY YOUR CUSTOMERS
   WON’T LIKE TO TEST IT EITHER.
   Unknown
   

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4. @MOLSJEROEN
   #DEVOXX #MOCKITO
   ALWAYS WRITE A TEST TO REPRODUCE A
   BUG BEFORE YOU FIX IT
   Robert C. Martin*
   

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5. @MOLSJEROEN
   #DEVOXX #MOCKITO
   GOAL
   UI
   USER
   WEBSERVICE
   Button press
   Success/failure
   Update UI LOGININTERFACE
   RESPONSE
   Login/logout command
   

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6. @MOLSJEROEN
   #DEVOXX #MOCKITO
   GOAL
   UI
   USER
   WEBSERVICE
   Button press
   Login/logout command Success/failure
   Update UI LOGININTERFACE
   RESPONSE
   

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7. @MOLSJEROEN
   #DEVOXX #MOCKITO
   WAY OF WORKING
   #DEVOXX #MOCKITO
   

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8. @MOLSJEROEN
   #DEVOXX #MOCKITO
   TEST REQUIREMENTS
   ▸ All tests must
   1. Run really fast
   2. Be small and focussed
   3. Reliable, not “flaky”
   ▸ Challenges: UI & WebService
   UI
   USER
   WEBSERVICE
   

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9. @MOLSJEROEN
   #DEVOXX #MOCKITO
   SOLUTION
   ▸ Isolate User
   ▸ Don’t include UI
   ▸ Replace WebService with dummy
   ▸ Mimic WebService behaviour
   ▸ => Verify interactions
   UI
   USER
   WEBSERVICE*
   

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10. @MOLSJEROEN
    #DEVOXX #MOCKITO
    DEFINITION: TEST DOUBLES
    ▸ Replace real class
    ▸ Same interface
    ▸ Different behaviour
    WEBSERVICE*
    WEBSERVICE
    public void login() {
    

    // NORMAL IMPL.
    

    }
    public void login() {
    

    // DO NOTHING
    

    }
    

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11. @MOLSJEROEN
    #DEVOXX #MOCKITO
    DEFINITION: TEST DOUBLES
    ▸ Replace real class
    ▸ Same interface
    ▸ Different behaviour
    WEBSERVICE
    public void login() {
    

    // NORMAL IMPL.
    

    }
    public void login() {
    

    // DO NOTHING
    

    }
    WEBSERVICE*
    

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12. @MOLSJEROEN
    #DEVOXX #MOCKITO
    DEFINITION: TEST DOUBLES
    ▸ Replace real class
    ▸ Same interface
    ▸ Different behaviour
    WEBSERVICE
    public void login() {
    

    // NORMAL IMPL.
    

    }
    public void login() {
    

    loginInterface.success();
    

    }
    WEBSERVICE*
    

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13. @MOLSJEROEN
    #DEVOXX #MOCKITO
    DEFINITION: TEST DOUBLES
    ▸ Replace real class
    ▸ Same interface
    ▸ Different behaviour
    WEBSERVICE
    public void login() {
    

    // NORMAL IMPL.
    

    }
    public void login() {
    

    throw new Exception();
    

    }
    WEBSERVICE*
    

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14. @MOLSJEROEN
    #DEVOXX #MOCKITO
    DEFINITION: MOCKS AND STUBS
    ▸ What is a mock?
    ▸ Generated class
    ▸ Doesn’t do anything
    ▸ Behaviour verification
    ▸ What is a stub?
    ▸ Handwritten class
    ▸ Returns predefined responses
    ▸ State verification
    

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15. @MOLSJEROEN
    #DEVOXX #MOCKITO
    MOCKITO
    #DEVOXX #MOCKITO
    

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16. @MOLSJEROEN
    #DEVOXX #MOCKITO
    Open source mocking framework that lets you write
    beautiful tests with a clean & simple API
    ▸ Documentation on mockito.org
    ▸ Source code on Github
    ▸ MIT license
    WHAT IS IT?
    

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17. @MOLSJEROEN
    #DEVOXX #MOCKITO
    WHY DRINK IT?
    ▸ Easy to use
    ▸ Very readable syntax
    ▸ No learning curve
    ▸ Annotation support
    ▸ Mature
    ▸ Large stackoverflow community
    ▸ Most popular Java / Android mocking framework
    

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18. @MOLSJEROEN
    #DEVOXX #MOCKITO
    HOW TO DRINK IT?
    ▸ PROJECT_HOME/build.gradle
    buildscript {

    repositories {

    jcenter()

    }

    }

    

    ▸ MODULE_HOME/build.gradle
    dependencies {

    ...
    

    testCompile “org.mockito:mockito-core:2.2.11"

    }
    

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19. @MOLSJEROEN
    #DEVOXX #MOCKITO
    HOW TO DRINK IT?
    ▸ PROJECT_HOME/build.gradle
    buildscript {

    repositories {

    jcenter()

    }

    }

    

    ▸ MODULE_HOME/build.gradle
    dependencies {

    ...
    

    testCompile “org.mockito:mockito-core:2.2.11"

    }
    

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20. @MOLSJEROEN
    #DEVOXX #MOCKITO
    INGREDIENTS
    #DEVOXX #MOCKITO
    

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21. @MOLSJEROEN
    #DEVOXX #MOCKITO
    INGREDIENTS
    ▸ Creating a mock
    ▸ Verifying interactions
    ▸ Stubbing methods
    ▸ Capturing arguments
    ▸ Mockito limitations
    

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22. @MOLSJEROEN
    #DEVOXX #MOCKITO
    INGREDIENTS
    ▸ Creating a mock
    ▸ Verifying interactions
    ▸ Stubbing methods
    ▸ Capturing arguments
    ▸ Mockito limitations
    

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23. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CREATING A MOCK
    import static org.mockito.Mockito.mock;
    @Test

    public void createMock() throws Exception {

    WebService mockWebService = mock(WebService.class);

    

    new User(mockWebService, 0, null);

    }
    

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24. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CREATING A MOCK
    import static org.mockito.Mockito.mock;
    @Test

    public void createMock() throws Exception {

    WebService mockWebService = mock(WebService.class);

    

    new User(mockWebService, 0, null);

    }
    

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25. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CREATING A MOCK
    import static org.mockito.Mockito.mock;
    @Test

    public void createMock() throws Exception {

    WebService mockWebService = mock(WebService.class);

    

    new User(mockWebService, 0, null);

    }
    

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26. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CREATING A MOCK - ANNOTATION
    @Rule

    public MockitoRule mockitoRule = MockitoJUnit.rule();

    

    @Mock

    private WebService mockWebService;
    @Test

    public void createMockUsingAnnotation() throws Exception {

    new User(mockWebService, 0, null);

    }
    

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27. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CREATING A MOCK - ANNOTATION
    @Rule

    public MockitoRule mockitoRule = MockitoJUnit.rule();

    

    @Mock

    private WebService mockWebService;
    @Test

    public void createMockUsingAnnotation() throws Exception {

    new User(mockWebService, 0, null);

    }
    

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28. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CREATING A MOCK - ANNOTATION
    @Rule

    public MockitoRule mockitoRule = MockitoJUnit.rule();

    

    @Mock

    private WebService mockWebService;
    @Test

    public void createMockUsingAnnotation() throws Exception {

    new User(mockWebService, 0, null);

    }
    

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29. @MOLSJEROEN
    #DEVOXX #MOCKITO
    INGREDIENTS
    ▸ Creating a mock
    ▸ Verifying interactions
    ▸ Stubbing methods
    ▸ Capturing arguments
    ▸ Mockito limitations
    

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30. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS
    @Test

    public void verifyInteractionTimes() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.logout();

    

    verify(mockWebService).logout();

    }
    

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31. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS
    @Test

    public void verifyInteractionTimes() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.logout();

    

    verify(mockWebService).logout();

    }
    

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32. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - TIMES
    @Test

    public void verifyInteractionTimes() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.logout();

    

    verify(mockWebService, times(1) ).logout();

    atLeast(1)

    atLeastOnce()

    atMost(1)

    only()

    never()

    }
    

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33. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - TIMES
    @Test

    public void verifyInteractionTimes() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.logout();

    

    verify(mockWebService, times(1) ).logout();

    atLeast(1)

    atLeastOnce()

    atMost(1)

    only()

    never()

    }
    ▸ Being overly restrictive makes tests brittle!
    

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34. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - PARAMETERS
    @Test

    public void verifyInteractionParameters() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    

    verify(mockWebService).login(USER_ID);

    }
    

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35. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - PARAMETERS
    @Test

    public void verifyInteractionParameters() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    

    verify(mockWebService).login(anyInt() );
    anyString()
    any(Response.class)

    }
    

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36. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - PARAMETERS
    @Test

    public void verifyInteractionParameters() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    

    verify(mockWebService).login(anyInt(), eq(PASSWORD));

    }
    ▸ One matcher -> all arguments need to be matchers
    

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37. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - PARAMETERS
    @Test

    public void verifyInteractionParameters() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    

    verify(mockWebService).login(gt(0) );

    lt(10000)
    leq(10000)

    }
    

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38. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - PARAMETERS
    @Test

    public void verifyInteractionParameters() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    

    verify(mockWebService).login(startsWith(“n1") );

    contains(“c3")
    matches("n[1-9]{1}c[1-9]{1}try")
    }
    

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39. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - PARAMETERS
    @Test

    public void verifyInteractionParameters() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    

    verify(mockWebService).login(isNotNull(Response.class)) );
    not(eq(0))
    not(eq(“12345678"))
    and(gt(0), lt(1000000000))

    }
    ▸ Mockito.Matchers
    ▸ Mockito.AdditionalMatchers
    

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40. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - ORDER
    @Test

    public void verifyInteractionOrder() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    user.logout();

    

    InOrder inOrder = inOrder(mockWebService);

    inOrder.verify(mockWebService).login();

    inOrder.verify(mockWebService).logout();

    }
    

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41. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - ORDER
    @Test

    public void verifyInteractionOrder() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    user.logout();

    

    InOrder inOrder = inOrder(mockWebService);

    inOrder.verify(mockWebService).login();

    inOrder.verify(mockWebService).logout();

    }
    

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42. @MOLSJEROEN
    #DEVOXX #MOCKITO
    VERIFYING INTERACTIONS - ORDER
    @Test

    public void verifyInteractionOrder() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    

    user.login(null);

    user.logout();

    

    InOrder inOrder = inOrder(mockWebService);

    inOrder.verify(mockWebService).login();

    inOrder.verify(mockWebService).logout();

    }
    

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43. @MOLSJEROEN
    #DEVOXX #MOCKITO
    INGREDIENTS
    ▸ Creating a mock
    ▸ Verifying interactions
    ▸ Stubbing methods
    ▸ Capturing arguments
    ▸ Mockito limitations
    

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44. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    @Test

    public void stubMethod() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    when(mockWebService.isOffline()).thenReturn(true);

    

    user.login(mockLoginInterface);

    

    verify(mockWebService, never()).login();

    }
    

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45. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    @Test

    public void stubMethod() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    when(mockWebService.isOffline()).thenReturn(true);

    

    user.login(mockLoginInterface);

    

    verify(mockWebService, never()).login();

    }
    

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46. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    @Test

    public void stubMethod() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    when(mockWebService.isOffline()).thenReturn(true);

    

    user.login(mockLoginInterface);

    

    verify(mockWebService, never()).login();

    }
    

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47. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    @Test

    public void stubMethod() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    when(mockWebService.isOffline()).thenReturn(true, false, true);

    

    user.login(mockLoginInterface);

    

    verify(mockWebService, never()).login();

    }
    

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48. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    @Test

    public void stubMethod() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    when(mockWebService.isOffline()).thenThrow(MyException.class);

    

    user.login(mockLoginInterface);

    

    verify(mockWebService, never()).login();

    }
    

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49. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    @Test

    public void stubMethod() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    when(mockWebService.isOffline()).then(new Answer() {

    int index = 0;

    

    @Override

    public Boolean answer(InvocationOnMock in) throws … {

    return index++ % 2 > 0;

    }

    });
    

    user.login(mockLoginInterface);

    

    verify(mockWebService, never()).login();

    }
    

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50. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    ▸ Normal syntax
    when(mockWebService.isOffline()).thenReturn(true);
    

    ▸ Alternative syntax
    doReturn(true).when(mockWebService).isOffline();
    

    ▸ BDD syntax
    given(mockWebService.isOffline()).willReturn(true);
    

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51. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    ▸ Normal syntax
    when(mockWebService.isOffline()).thenReturn(true);
    

    ▸ Alternative syntax
    doReturn(true).when(mockWebService).isOffline();
    

    ▸ BDD syntax
    given(mockWebService.isOffline()).willReturn(true);
    

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52. @MOLSJEROEN
    #DEVOXX #MOCKITO
    STUBBING METHODS
    ▸ Normal syntax
    when(mockWebService.isOffline()).thenReturn(true);
    

    ▸ Alternative syntax
    doReturn(true).when(mockWebService).isOffline();
    

    ▸ BDD syntax
    given(mockWebService.isOffline()).willReturn(true);
    

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53. @MOLSJEROEN
    #DEVOXX #MOCKITO
    INGREDIENTS
    ▸ Creating a mock
    ▸ Verifying interactions
    ▸ Stubbing methods
    ▸ Capturing arguments
    ▸ Mockito limitations
    

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54. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - PROBLEM STATEMENT
    UI
    USER
    WEBSERVICE*
    Button press
    Success/failure
    Update UI LOGININTERFACE*
    RESPONSE
    Login command
    

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55. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - PROBLEM STATEMENT
    UI
    USER
    WEBSERVICE*
    Button press
    Success/failure
    Update UI LOGININTERFACE*
    RESPONSE
    Login command
    

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56. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - CHALLENGE
    public void login(final LoginInterface loginInterface) {
    Response response = new Response() {

    @Override

    public void onRequestCompleted(…) {

    ...
    }
    }

    webService.login(userId, password, response);

    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    

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57. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - CHALLENGE
    public void login(final LoginInterface loginInterface) {
    Response response = new Response() {

    @Override

    public void onRequestCompleted(…) {

    ...
    }
    }

    webService.login(userId, password, response);

    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    

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58. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - PROBLEM STATEMENT
    public class Response {
    

    public void onRequestCompleted(boolean success, String data){

    if (success) {

    loginInterface.onLoginSuccess();

    } else {

    loginInterface.onLoginFailed();

    }

    }
    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    

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59. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - PROBLEM STATEMENT
    public class Response {
    

    public void onRequestCompleted(boolean success, String data){

    if (success) {

    loginInterface.onLoginSuccess();

    } else {

    loginInterface.onLoginFailed();

    }

    }
    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    

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60. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - SOLUTION
    UI
    USER
    WEBSERVICE*
    Button press
    Success/failure
    Update UI LOGININTERFACE*
    RESPONSE
    1 Login command
    

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61. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - SOLUTION
    UI
    USER
    WEBSERVICE*
    Button press
    Success/failure
    Update UI LOGININTERFACE*
    2
    Login command
    Capture
    response
    RESPONSE
    

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62. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - SOLUTION
    UI
    USER
    Button press
    Success/failure
    Update UI
    3
    WEBSERVICE*
    LOGININTERFACE*
    RESPONSE
    Login command
    

    View Slide

63. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS - SOLUTION
    UI
    USER
    WEBSERVICE*
    Button press
    Success/failure
    Update UI LOGININTERFACE*
    RESPONSE
    4
    Login command
    

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64. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS
    @Test

    public void captureArguments() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    user.login(mockLoginInterface);

    verify(mockWebService).login(responseCaptor.capture());

    Response response = responseCaptor.getValue();

    

    response.onRequestCompleted(true);

    

    verify(mockLoginInterface).onLoginSuccess();

    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    

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65. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS
    @Captor

    private ArgumentCaptor responseCaptor;
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    0
    

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66. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS
    @Test

    public void captureArguments() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    user.login(mockLoginInterface);

    verify(mockWebService).login(responseCaptor.capture());

    Response response = responseCaptor.getValue();

    

    response.onRequestCompleted(true);

    

    verify(mockLoginInterface).onLoginSuccess();

    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    1
    

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67. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS
    @Test

    public void captureArguments() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    user.login(mockLoginInterface);

    verify(mockWebService).login(responseCaptor.capture());

    Response response = responseCaptor.getValue();

    

    response.onRequestCompleted(true);

    

    verify(mockLoginInterface).onLoginSuccess();

    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    2
    

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68. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS
    @Test

    public void captureArguments() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    user.login(mockLoginInterface);

    verify(mockWebService).login(responseCaptor.capture());

    Response response = responseCaptor.getValue();

    

    response.onRequestCompleted(true);

    

    verify(mockLoginInterface).onLoginSuccess();

    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    3
    

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69. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CAPTURING ARGUMENTS
    @Test

    public void captureArguments() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    user.login(mockLoginInterface);

    verify(mockWebService).login(responseCaptor.capture());

    Response response = responseCaptor.getValue();

    

    response.onRequestCompleted(true);

    

    verify(mockLoginInterface).onLoginSuccess();

    }
    UI USER WEBSERVICE*
    LOGININTERFACE* RESPONSE
    4
    

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70. @MOLSJEROEN
    #DEVOXX #MOCKITO
    INGREDIENTS
    ▸ Creating a mock
    ▸ Verifying interactions
    ▸ Stubbing methods
    ▸ Capturing arguments
    ▸ Mockito limitations
    

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71. @MOLSJEROEN
    #DEVOXX #MOCKITO
    MOCKITO LIMITATIONS
    ▸ Unable to mock
    ▸ final classes => opt-in with Mockito 2.x
    ▸ final methods => opt-in with Mockito 2.x
    ▸ static methods
    ▸ private methods
    ▸ hashCode() and equals()
    

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72. @MOLSJEROEN
    #DEVOXX #MOCKITO
    ADVANCED MOCKITO
    #DEVOXX #MOCKITO
    

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73. @MOLSJEROEN
    #DEVOXX #MOCKITO
    ADVANCED MOCKITO
    ▸ Testing UI
    ▸ Running Mockito on an Android device
    ▸ Custom Matchers
    ▸ Testing final and static
    ▸ Testing data
    ▸ New creation
    ▸ Power tips
    

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74. @MOLSJEROEN
    #DEVOXX #MOCKITO
    ADVANCED MOCKITO
    ▸ Testing UI
    ▸ Running Mockito on an Android device
    ▸ Custom Matchers
    ▸ Testing final and static
    ▸ Testing data
    ▸ New creation
    ▸ Power tips
    

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75. @MOLSJEROEN
    #DEVOXX #MOCKITO
    ▸ Model View Presenter
    ▸ Mock view & model
    ▸ Fully test presenter
    ▸ UI == “pass through”
    ▸ Dependency injection
    ▸ Only “inward pointing” dependencies
    TESTING UI
    MODEL
    VIEW
    PRESENTER
    VIEW
    IMPLEMENTATION
    

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76. @MOLSJEROEN
    #DEVOXX #MOCKITO
    ADVANCED MOCKITO
    ▸ Testing UI
    ▸ Running Mockito on an Android device
    ▸ Custom Matchers
    ▸ Testing final and static
    ▸ Testing data
    ▸ New creation
    ▸ Power tips
    

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77. @MOLSJEROEN
    #DEVOXX #MOCKITO
    RUNNING MOCKITO ON AN ANDROID DEVICE
    ▸ MODULE_HOME/build.gradle
    defaultConfig {

    …
    

    testInstrumentationRunner 

    "android.support.test.runner.AndroidJUnitRunner"

    }
    dependencies {

    …
    

    androidTestCompile 'com.android.support.test:runner:0.5'

    androidTestCompile 'com.android.support.test:rules:0.5'

    androidTestCompile 'org.mockito:mockito-core:1.10.19'

    androidTestCompile 'com.crittercism.dexmaker:dexmaker:1.4'

    androidTestCompile 'com.crittercism.dexmaker:dexmaker-dx:1.4'
    androidTestCompile 'com.crittercism.dexmaker:dexmaker-mockito:1.4'

    }
    

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78. @MOLSJEROEN
    #DEVOXX #MOCKITO
    RUNNING MOCKITO ON AN ANDROID DEVICE
    ▸ MODULE_HOME/build.gradle
    defaultConfig {

    …
    

    testInstrumentationRunner 

    "android.support.test.runner.AndroidJUnitRunner"

    }
    dependencies {

    …
    

    androidTestCompile 'com.android.support.test:runner:0.5'

    androidTestCompile 'com.android.support.test:rules:0.5'

    androidTestCompile 'org.mockito:mockito-core:1.10.19'

    androidTestCompile 'com.crittercism.dexmaker:dexmaker:1.4'

    androidTestCompile 'com.crittercism.dexmaker:dexmaker-dx:1.4'
    androidTestCompile 'com.crittercism.dexmaker:dexmaker-mockito:1.4'

    }
    

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79. @MOLSJEROEN
    #DEVOXX #MOCKITO
    RUNNING MOCKITO ON AN ANDROID DEVICE
    ▸ MODULE_HOME/build.gradle
    defaultConfig {

    …
    

    testInstrumentationRunner 

    "android.support.test.runner.AndroidJUnitRunner"

    }
    dependencies {

    …
    

    androidTestCompile 'com.android.support.test:runner:0.5'

    androidTestCompile 'com.android.support.test:rules:0.5'

    androidTestCompile 'org.mockito:mockito-core:1.10.19'

    androidTestCompile 'com.crittercism.dexmaker:dexmaker:1.4'

    androidTestCompile 'com.crittercism.dexmaker:dexmaker-dx:1.4'
    androidTestCompile 'com.crittercism.dexmaker:dexmaker-mockito:1.4'

    }
    

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80. @MOLSJEROEN
    #DEVOXX #MOCKITO
    ADVANCED MOCKITO
    ▸ Testing UI
    ▸ Running Mockito on an Android device
    ▸ Custom Matchers
    ▸ Testing final and static
    ▸ Testing data
    ▸ New creation
    ▸ Power tips
    

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81. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER - LIST CONTAINS
    public class ListContains implements ArgumentMatcher {

    

    private final T object;

    

    public ListContains(T object) {

    this.object = object;

    }

    

    public boolean matches(List list) {

    return list.contains(object);

    }

    

    public String toString() {

    //printed in verification errors

    return "[list doesn't contain object]";

    }

    }
    

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82. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER - LIST CONTAINS
    public class ListContains implements ArgumentMatcher {

    

    private final T object;

    

    public ListContains(T object) {

    this.object = object;

    }

    

    public boolean matches(List list) {

    return list.contains(object);

    }

    

    public String toString() {

    //printed in verification errors

    return "[list doesn't contain object]";

    }

    }
    

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83. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER - LIST CONTAINS
    public class ListContains implements ArgumentMatcher {

    

    private final T object;

    

    public ListContains(T object) {

    this.object = object;

    }

    

    public boolean matches(List list) {

    return list.contains(object);

    }

    

    public String toString() {

    //printed in verification errors

    return "[list doesn't contain object]";

    }

    }
    

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84. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER - LIST CONTAINS
    public class ListContains implements ArgumentMatcher {

    

    private final T object;

    

    public ListContains(T object) {

    this.object = object;

    }

    

    public boolean matches(List list) {

    return list.contains(object);

    }

    

    public String toString() {

    //printed in verification errors

    return "[list doesn't contain object]";

    }

    }
    

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85. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER - LIST CONTAINS
    public class ListContains implements ArgumentMatcher {

    

    private final T object;

    

    public ListContains(T object) {

    this.object = object;

    }

    

    public boolean matches(List list) {

    return list.contains(object);

    }

    

    public String toString() {

    //printed in verification errors

    return "[list doesn't contain object]";

    }

    }
    

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86. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER - STATIC METHOD
    public class ListMatchers {

    

    @Nullable

    public static List listContains(K object) {

    return argThat(new ListContains<>(object));

    }

    }
    

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87. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER - STATIC METHOD
    public class ListMatchers {

    

    @Nullable

    public static List listContains(K object) {

    return argThat(new ListContains<>(object));

    }

    }
    

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88. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER - STATIC METHOD
    public class ListMatchers {

    

    @Nullable

    public static List listContains(K object) {

    return argThat(new ListContains<>(object));

    }

    }
    

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89. @MOLSJEROEN
    #DEVOXX #MOCKITO
    TRADITIONAL TEST - ARGUMENTCAPTOR
    @Test
    public void argumentCaptorTest() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    ArgumentCaptor> listCaptor = ...;

    String expectedMessage = "Test message";

    

    user.sendMessage(expectedMessage);

    

    verify(mockWebService).sendMessages(listCaptor.capture());

    List messages = listCaptor.getValue();

    String actualMessage = messages.get(0);

    

    assertEquals(expectedMessage, actualMessage);

    }
    

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90. @MOLSJEROEN
    #DEVOXX #MOCKITO
    TRADITIONAL TEST - ARGUMENTCAPTOR
    @Test
    public void argumentCaptorTest() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    ArgumentCaptor> listCaptor = ...;

    String expectedMessage = "Test message";

    

    user.sendMessage(expectedMessage);

    

    verify(mockWebService).sendMessages(listCaptor.capture());

    List messages = listCaptor.getValue();

    String actualMessage = messages.get(0);

    

    assertEquals(expectedMessage, actualMessage);

    }
    

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91. @MOLSJEROEN
    #DEVOXX #MOCKITO
    TRADITIONAL TEST - ARGUMENTCAPTOR
    @Test
    public void argumentCaptorTest() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    ArgumentCaptor> listCaptor = ...;

    String expectedMessage = "Test message";

    

    user.sendMessage(expectedMessage);

    

    verify(mockWebService).sendMessages(listCaptor.capture());

    List messages = listCaptor.getValue();

    String actualMessage = messages.get(0);

    

    assertEquals(expectedMessage, actualMessage);

    }
    

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92. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER TEST
    @TestTest

    public void customMatcherTest() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    String message = "Test message";

    user.sendMessage(message);

    

    verify(mockWebService).sendMessages(listContains(message));

    }
    

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93. @MOLSJEROEN
    #DEVOXX #MOCKITO
    CUSTOM MATCHER TEST
    @TestTest

    public void customMatcherTest() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);

    String message = "Test message";

    user.sendMessage(message);

    

    verify(mockWebService).sendMessages(listContains(message));

    }
    RELATED BLOGPOSTS
    

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94. @MOLSJEROEN
    #DEVOXX #MOCKITO
    ADVANCED MOCKITO
    ▸ Testing UI
    ▸ Running Mockito on an Android device
    ▸ Custom Matchers
    ▸ Testing final and static
    ▸ Testing data
    ▸ New creation
    ▸ Power tips
    

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95. @MOLSJEROEN
    #DEVOXX #MOCKITO
    TESTING FINAL METHODS / CLASSES
    public class Handler {

    

    public Handler() {};

    

    public final boolean post(Runnable r) {

    // internal implementation

    }

    

    public final boolean sendMessage(Message msg) {

    // internal implementation

    }

    }
    

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96. @MOLSJEROEN
    #DEVOXX #MOCKITO
    TESTING FINAL METHODS / CLASSES
    public class Handler {

    

    public Handler() {};

    

    public final boolean post(Runnable r) {

    // internal implementation

    }

    

    public final boolean sendMessage(Message msg) {

    // internal implementation

    }

    }
    

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97. @MOLSJEROEN
    #DEVOXX #MOCKITO
    TESTING FINAL METHODS / CLASSES
    public class HandlerWrapper {

    

    private final Handler handler;

    

    public HandlerWrapper() {

    handler = new Handler();

    }

    

    public boolean post(Runnable r) {

    return handler.post(r);

    }

    

    public boolean sendMessage(Message msg) {

    return handler.sendMessage(msg);

    }

    }
    

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98. @MOLSJEROEN
    #DEVOXX #MOCKITO
    TESTING FINAL METHODS / CLASSES
    public class HandlerWrapper {

    

    private final Handler handler;

    

    public HandlerWrapper() {

    handler = new Handler();

    }

    

    public boolean post(Runnable r) {

    return handler.post(r);

    }

    

    public boolean sendMessage(Message msg) {

    return handler.sendMessage(msg);

    }

    }
    

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99. @MOLSJEROEN
    #DEVOXX #MOCKITO
    TESTING FINAL METHODS / CLASSES
    public class HandlerWrapper {

    

    private final Handler handler;

    

    public HandlerWrapper() {

    handler = new Handler();

    }

    

    public boolean post(Runnable r) {

    return handler.post(r);

    }

    

    public boolean sendMessage(Message msg) {

    return handler.sendMessage(msg);

    }

    }
    

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100. @MOLSJEROEN
     #DEVOXX #MOCKITO
     TESTING FINAL METHODS/CLASSES - MOCKITO 2.X
     ▸ Opt-in process
     ▸ Create new file
     ▸ name: org.mockito.plugins.MockMaker
     ▸ path: src/test/resources/mockito-extensions
     ▸ contents: mock-maker-inline
     

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101. @MOLSJEROEN
     #DEVOXX #MOCKITO
     TESTING STATIC METHODS
     public class NativeCamera {

     

     private Camera camera = null;

     

     public Camera getNativeCamera() {

     return camera;

     }

     

     public void openNativeCamera() throws RuntimeException {

     camera = Camera.open(CameraInfo.CAMERA_FACING_BACK);

     }

     

     public void releaseNativeCamera() {

     camera.release();

     }

     }
     

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102. @MOLSJEROEN
     #DEVOXX #MOCKITO
     TESTING STATIC METHODS
     public class NativeCamera {

     

     private Camera camera = null;

     

     public Camera getNativeCamera() {

     return camera;

     }

     

     public void openNativeCamera() throws RuntimeException {

     camera = Camera.open(CameraInfo.CAMERA_FACING_BACK);

     }

     

     public void releaseNativeCamera() {

     camera.release();

     }

     }
     

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103. @MOLSJEROEN
     #DEVOXX #MOCKITO
     ADVANCED MOCKITO
     ▸ Testing UI
     ▸ Running Mockito on an Android device
     ▸ Custom Matchers
     ▸ Testing final and static
     ▸ Testing data
     ▸ New creation
     ▸ Power tips
     

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104. @MOLSJEROEN
     #DEVOXX #MOCKITO
     TESTING DATA
     @Test

     public void mockData() throws Exception {

     UserData mock = mock(UserData.class);

     when(mock.getFirstName()).thenReturn("FirstName");

     when(mock.getLastName()).thenReturn("LastName");

     when(mock.getUserId()).thenReturn(1111007);

     

     when(mock.getStreet()).thenReturn("StreetName");

     when(mock.getHouseNumber()).thenReturn(1);

     when(mock.getCity()).thenReturn("City");

     when(mock.getCountry()).thenReturn("Country");

     

     // Use mock in further test

     }
     

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105. @MOLSJEROEN
     #DEVOXX #MOCKITO
     TESTING DATA
     @Test

     public void testData() throws Exception {

     UserData userData = new TestUserData();

     

     // use mock in further test

     }
     public class TestUserData extends UserData {
     @Override

     public String getFirstName() {

     return "FirstName";

     }
     

     ...
     }
     

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106. @MOLSJEROEN
     #DEVOXX #MOCKITO
     TESTING DATA
     @Test

     public void testData() throws Exception {

     UserData userData = new TestUserData();

     

     // use mock in further test

     }
     public class TestUserData extends UserData {
     @Override

     public String getFirstName() {

     return "FirstName";

     }
     

     ...
     }
     

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107. @MOLSJEROEN
     #DEVOXX #MOCKITO
     ADVANCED MOCKITO
     ▸ Testing UI
     ▸ Running Mockito on an Android device
     ▸ Custom Matchers
     ▸ Testing final and static
     ▸ Testing data
     ▸ New creation
     ▸ Power tips
     

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108. @MOLSJEROEN
     #DEVOXX #MOCKITO
     NEW CREATION
     public User(int userId, String password) {

     this.webService = new WebService();

     }
     ▸ Internal created objects
     ▸ almost impossible to test
     ▸ avoid for long lived objects
     

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109. @MOLSJEROEN
     #DEVOXX #MOCKITO
     NEW CREATION
     public User(int userId, String password) {

     this.webService = new WebService();

     }
     ▸ Internal created objects
     ▸ almost impossible to test
     ▸ avoid for long lived objects
     

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110. @MOLSJEROEN
     #DEVOXX #MOCKITO
     NEW CREATION
     public User(int userId, String password) {

     this.webService = new WebService();

     }
     ▸ Dependency injection
     public User(WebService webService, int user, String password) {

     if (webService == null) {

     throw new RuntimeException("Webservice required");

     }

     this.webService = webService;

     }
     

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111. @MOLSJEROEN
     #DEVOXX #MOCKITO
     NEW CREATION
     public User(int userId, String password) {

     this.webService = new WebService();

     }
     ▸ Factory pattern
     public User(WebServiceFactory factory, int user, String pw) {

     this.webService = factory.createWebService();

     }
     

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112. @MOLSJEROEN
     #DEVOXX #MOCKITO
     ADVANCED MOCKITO
     ▸ Testing UI
     ▸ Running Mockito on an Android device
     ▸ Custom Matchers
     ▸ Testing final and static
     ▸ Testing data
     ▸ New creation
     ▸ Power tips
     

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113. @MOLSJEROEN
     #DEVOXX #MOCKITO
     IF YOU’RE NOT WRITING TESTS, YOU’RE
     WRITING INSTANT LEGACY.
     Michael feathers*
     

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114. @MOLSJEROEN
     #DEVOXX #MOCKITO
     POWER TIPS
     ▸ Avoid singletons
     ▸ Avoid Android instrumentation tests
     ▸ Isolate non testable code
     ▸ Don’t use Spies
     ▸ Don’t nest mocks
     ▸ Avoid using “For testing methods”
     

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115. @MOLSJEROEN
     #DEVOXX #MOCKITO
     WRAP UP
     #DEVOXX #MOCKITO
     

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116. @MOLSJEROEN
     #DEVOXX #MOCKITO
     IT IS BETTER TO HAVE A SIMPLE TEST THAT
     WORKS THAN A COMPLICATED TEST THAT
     SEEMS TO WORK.
     Mockito documentation
     

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117. @MOLSJEROEN
     #DEVOXX #MOCKITO
     CONCLUSION
     ▸ Mockito makes mocking & stubbing easy
     ▸ Avoid creating internal objects
     ▸ Choose a good testing strategy
     ▸ Don’t overuse the power features
     ▸ Keep unit tests small and focussed
     ▸ Consider refactoring
     ▸ Prefer tests on the java VM
     

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118. @MOLSJEROEN
     #DEVOXX #MOCKITO
     REFERENCES
     ▸ Mockito homepage http://mockito.org/
     ▸ Mockito reference card https://dzone.com/refcardz/mockito
     ▸ Dexmaker https://github.com/crittercism/dexmaker
     ▸ Sample code
     ▸ MockitoExample https://github.com/JeroenMols/MockitoExample
     ▸ LandscapeVideoCamera https://github.com/JeroenMols/LandscapeVideoCamera
     ▸ MockitoColletionMatchers https://github.com/JeroenMols/MockitoCollectionMatchers
     

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119. @MOLSJEROEN
     #DEVOXX #MOCKITO
     IMAGE CREDITS
     ▸ Mojito

     https://indraneescookingcorner.blogspot.be/2014/08/virgin-mojito.html
     ▸ Philips Hue living room

     http://www.philips.de
     ▸ Bartender set

     http://www.vinspireuk.com/2014/12/cocktail-gifts-for-cocktail-lovers.html
     ▸ Mojito ingredients

     https://www.nelleulla.com/lv-en/products/truffles/4-mojito-truffle
     ▸ Mockito Mojito

     http://www.seedylawyer.com/history-of-hemingways-mojitos/
     ▸ Raspberry Mojito

     http://goodpixcool.com/raspberry+mojito+in+a+bottle?image=99002602
     ▸ Drinking Mojito

     https://www.lancerskincare.com/blog/10-ways-to-age-your-skin-prematurely/
     

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120. @MOLSJEROEN
     #DEVOXX #MOCKITO
     MANY THANKS
     ▸ Jeroen Mols (Belgium)
     ▸ @MolsJeroen
     ▸ http://jeroenmols.com/blog
     

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