Testable Android Architecture (Part 2)

We have so many testing tools for Android now including JUnit, Mockito, Robolectric, and Espresso. But how can you design your application to leverage each one most effectively? This talk introduces a modified version of Model View Presenter (MVP) to help organize your code to be more flexible, maintainable, and testable.

The first half of this talk will recap my presentation from Droidcon NYC 2016. The second half will explore advanced use cases, in-depth code samples, and audience Q&A.

Transcript

1. Testable Android
   Architecture
   (Part 2)
   15 Nov 2016 / Chuck Greb
   

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2. Clean code
   Software Craftsmanship
   

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3. Art is anything you can do
   well. Anything you can do
   with Quality.
   “
   ”
   - Robert M. Pirsig
   

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5. → MVC Model View Controller
   → MVP Model View Presenter
   → MVVM Model View ViewModel
   Clean Architecture
   Design patterns
   

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6. Building your first app
   

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7. Activity
   

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8. Activity
   Activity
   Lifecycle
   System
   Services
   

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9. Activity
   EditText
   Button
   Activity
   Lifecycle
   System
   Services
   

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10. Activity
    EditText
    Button
    Web
    Service
    Storage
    AsyncTask
    Activity
    Lifecycle
    System
    Services
    

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11. Fragment
    Activity
    EditText
    Button
    Web
    Service
    Storage
    AsyncTask
    Activity
    Lifecycle
    System
    Services
    Fragment
    Fragment
    Lifecycle
    

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12. Fragment
    Activity
    EditText
    Button
    Web
    Service
    Storage
    AsyncTask
    Activity
    Lifecycle
    System
    Services
    Fragment
    Fragment
    Lifecycle
    User
    Input
    Input
    Validation
    

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13. Fragment
    Activity
    Web
    Service
    Storage
    AsyncTask
    Activity
    Lifecycle
    System
    Services
    Fragment
    Fragment
    Lifecycle
    User
    Input
    setRetainInstance(true)
    EditText
    Button
    Input
    Validation
    

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14. Fragment
    Activity
    Web
    Service
    Storage
    AsyncTask
    Activity
    Lifecycle
    System
    Services
    Fragment
    Fragment
    Lifecycle
    User
    Input
    setRetainInstance(true)
    Intent
    Parcelable
    Extras
    EditText
    Button
    Input
    Validation
    

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15. Web
    Service
    Storage
    Activity
    Fragment
    Fragment
    AsyncTask
    setRetainInstance(true)
    Activity
    Lifecycle
    Fragment
    Lifecycle
    System
    Services
    User
    Input
    Intent
    Activity
    Instrumentation
    TestCase2
    Parcelable
    Extras
    EditText
    Button
    Input
    Validation
    

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17. There has to be a
    better way
    

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18. Activity Logic
    

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19. Activity Logic
    Data
    

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20. Activity Logic
    Data
    View
    

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21. View
    (Activity)
    Controller
    (Logic)
    Model
    (Data)
    View
    

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22. View
    (Activity)
    Presenter
    (Logic)
    Model
    (Data)
    View
    

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23. View
    (Activity)
    ViewModel
    (Logic)
    Model
    (Data)
    View
    

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24. - Phil Karlton
    There are only two hard
    problems in computer science:
    cache invalidation and naming
    things
    “
    ”
    

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25. Clean Architecture
    Model View
    Presenter Controller
    MVP(C)
    

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26. Controller
    (Activity)
    Presenter
    (Logic)
    Model
    (Data)
    View
    

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27. Activity Presenter
    (Logic)
    Model
    (Data)
    View
    Controller
    

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28. Web
    Service
    Storage
    Activity
    Activity
    Lifecycle
    System
    Services
    User
    Input
    Presenter
    View Model
    Controller
    Button
    EditText
    Thread
    Input
    Validation
    start()
    

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29. Web
    Service
    Storage
    Activity
    Activity
    Lifecycle
    System
    Services
    User
    Input
    Presenter
    View Model
    Controller
    Button
    EditText
    Input
    Validation
    Thread
    start()
    

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30. Testings
    Models & Presenters
    JUnit + Mockito
    

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31. Mock
    Service
    Mock
    Storage
    Test
    Controller
    Presenter
    Model
    Controller
    JUnit
    TestRunner
    Runnable
    run()
    

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32. A test is not a unit test if:
    → It talks to the database
    → It communicates across the network
    → It touches the file system
    → It can't run at the same time as any of
    your other unit tests
    → You have to do special things to your
    environment (such as editing config files)
    to run it.
    Michael Feathers, 2005
    A Set of Unit Test Rules
    

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33. Testing
    Activities & Views
    Robolectric
    

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34. Activity
    Robolectric
    TestRunner
    Robolectric
    Runtime
    Environment
    Simulated
    Input
    Stub
    Presenter
    View
    Button
    EditText
    Input
    Validation
    

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35. Demo App
    https://github.com/ecgreb/mvpc
    

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36. Q & A
    

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37. What is the best way to
    manage presenter scope or
    lifecycle?
    “
    ”
    

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38. → Global singleton
    → Scoped singleton
    → View State Manager
    Q & A
    What is the best way to manage presenter scope or lifecycle?
    

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39. Web
    Service
    Storage
    Activity
    Activity
    Lifecycle
    System
    Services
    User
    Input
    Presenter
    View Model
    Controller
    Button
    EditText
    Thread
    Input
    Validation
    start()
    

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40. Web
    Service
    Storage
    Activity
    Activity
    Lifecycle
    System
    Services
    User
    Input
    Presenter
    View Model
    Controller
    Button
    EditText
    Thread
    Input
    Validation
    start()
    ViewState
    Manager
    (VSM)
    

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41. Can a view have its own
    presenter?
    “
    ”
    

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42. → True Model-View-Presenter
    → One presenter instance per view
    Q & A
    Can a view have its own presenter?
    

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43. View
    Presenter
    Activity
    Activity
    Lifecycle
    System
    Services
    User
    Input
    Main
    Presenter
    View
    Controller
    Button
    EditText
    Input
    Validation
    Model
    

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44. How do you communicate
    between multiple
    presenters?
    “
    ”
    

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45. → Pass the message “around the horn”
    → Event bus
    Q & A
    How do you communicate between multiple presenters?
    

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46. Search
    View
    Search
    Presenter
    Main
    Activity
    Main
    Presenter
    Navigation
    View
    Navigation
    Presenter
    

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47. Search
    View
    Search
    Presenter
    Main
    Activity
    Main
    Presenter
    Navigation
    View
    Navigation
    Presenter
    Event
    Bus
    

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48. Eraser Map
    

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51. → Choose an architecture appropriate to
    your use case
    → Write tests that work in concert with
    your architecture
    → Don’t be overly dogmatic
    Conclusion
    So which architecture and testing strategy should I use for my app?
    

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52. Start where you are
    

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