1. Iordanis Giannakakis
@iordanis_g
Device Fragmentation vs Clean Code

2. Introduction
• Iordanis “Jordan” Giannakakis
• Android Team Lead at Shazam
• @iordanis_g

3. How Shazam works

4. Running order
• What is fragmentation & clean code?
• Make the most of the Android platform
• DIY: Compatible cross-version features
• Handle complexity with MVP
• Write tests that cover all devices
• Q & A

5. Running order
• What is fragmentation & clean code?
• Make the most of the Android platform
• DIY: Compatible cross-version features
• Handle complexity with MVP
• Write tests that cover all devices
• Q & A

6. Device fragmentation

7. Distribution of OS versions (03/14)
• KitKat only 2x as
big as Froyo (2010)
– 2.5% vs. 1.2%
• Gingerbread still
20% (2010)

8. Screen variations

9. Variety of capabilities

10. Variety of capabilities

11. Does diversification matter?
• Variety is the power of Android
• Google Play Services updates
• OS features as apps
• Compatibility libraries

12. Bad code

13. Bad code
• Big ‘If’ statements, heavily branched
• Unmaintainable
• Duplication
• Mixed concerns
• Untestable

14. Clean code

15. Clean code
• Easy to change
• Object model
• Single responsibilities
• Reusable
• Testable

16. Code quality: Is it a concern really?
• Short-term projects
• Individually developed
• Lean
• A/B testing

17. Code quality: Is it a concern really?
• Codebase gets bigger
• Need to grow team
• No tests
• Code becomes legacy

18. Code quality at Shazam

19. Running order
• What is fragmentation & clean code?
• Make the most of the Android platform
• DIY: Compatible cross-version features
• Handle complexity with MVP
• Write tests that cover all devices
• Q & A

20. Resource System
res/

21. Some resource types
• Layouts
• Drawables
• Values
– Attributes
– Colours
– Strings
– Styles

22. Some resource qualifiers
• Locale
• Screen
– Size
– Density
– Orientation
– Ratio
• Platform version

23. Customise UI

24. Switchable components

25. Switchable components

26. Code example:
Resource System
github.com/iordanis/androidCleanCode

27. What we have gained
• Less code
• Separated presentation to logic
• Flexible UI

28. Running order
• What is fragmentation & clean code?
• Make the most of the Android platform
• DIY: Compatible cross-version features
• Handle complexity with MVP
• Write tests that cover all devices
• Q & A

29. API change
SharedPreferences.Editor
• commit() – slow, since v1
• apply() – fast, since v9

30. Compatibility libraries
• Backport features to old OS versions
• Version checking and graceful degradation
• Same package structure, different namespace
– android.app
– android.support.v2.app
• “Deprecated by design”

31. Compatibility libraries
• Official Libraries
– Support v4, v8, v13
– AppCompat v7
• 3rd party:
– ActionbarSherlock
– Nineoldandroids

32. Dependency Inject, Yourself (DIY)
• Break hardcoded dependencies
• What vs how
• Behaviour vs implementation
• Swappable dependencies for test and
production runtimes

33. Without Dependency Injection
Client
Feature X Feature X

34. Dependency Injection
Client
Injector
Feature X
Interface

35. Drive for DIY
• Fast
• Simple
• No magic necessary
• Pure Java!
• Run Android code on JVM for tests
java.lang.RuntimeException: Stub!

36. Code example:
SharedPreferences
Compatibility
github.com/iordanis/androidCleanCode

37. What we have gained
• Eliminated ‘ifs’ from production code
• Maintainability
• Testable code
• Reusable code
• More users

38. Running order
• What is fragmentation & clean code?
• Make the most of the Android platform
• DIY: Compatible cross-version features
• Handle complexity with MVP
• Write tests that cover all devices
• Q & A

39. Capabilities example – Google Play Services

40. Activity lifecycle
• Complex
• Few callbacks
relevant

41. Issues with presentation complexity
• Compounds complexity of lifecycle
• Testing presentation logic difficult
• Unfulfilled dependencies when in JVM
java.lang.RuntimeException: Stub!
• Robolectric is the only option

42. The MVP pattern
Presenter
Model View

43. The MVP pattern, with Android
Presenter
Model
View
start
stop
Android

44. Drive for MVP
• Make presentation logic testable
• Avoid Android dependencies
• No need to test the “slave” view
• Avoid Robolectric

45. Code example:
MVP
github.com/iordanis/androidCleanCode

46. What we have gained
• Separation of concerns
• Testable presentation logic
• Reusable code
• Avoiding need for dependencies when running
Android tests on JVM

47. Running order
• What is fragmentation & clean code?
• Make the most of the Android platform
• DIY: Compatible cross-version features
• Handle complexity with MVP
• Write tests that cover all devices
• Q & A

48. Test requirements
• Expressive
• Flexible
• Fast
• Helpful diagnostics

49. Testing Android apps
• Unit
• Integration
• System

50. System tests
• Instrumentation framework
• Robotium & Espresso
• gwen

51. Behaviour tests
• Given: arrange
• When: act
• Then: assert

52. Example
Given the server returns a track
When the user taps the Shazam button
Then the user sees the track result

53. gwen
given(server).returnsATrack()
when(user).tapsTheShazamButton()
then(user).seesTheTrackResult()
https://github.com/shazam/gwen

54. Phone behaviour

55. Tablet behaviour

56. Code example:
System Tests
github.com/iordanis/androidCleanCode

57. Test speed
• All tests on all devices
– not always necessary
• Device clouds
• Gradle
• Maven

58. Spoon
http://square.github.io/spoon/

59. Fork
• Inspired by Spoon
• Infinitely scalable
– 1 test / 3secs
• Pooled execution
– Create pool for any device parameter

60. Fork

61. Diagnostics

62. Flexibility
@SkipOnDevice(
deviceType = TABLET_LARGE)
@SkipOnDevice(
playServices = NOT_AVAILABLE)

63. Summary
• Relationship of fragmentation & clean code
• How to make the most of Android
• How to write compatible code cleanly
• How to apply the MVP pattern
• How to write awesome automation tests

64. Notes
@iordanis_g
+IordanisGiannakakis
Code examples:
github.com/iordanis/androidCleanCode
Hiring...

65. References
• Responsible Design For Android:
https://leanpub.com/ResponsibleDesignAndroid-Part1
• 50 Android Hacks: http://www.manning.com/sessa/
• Google I/O 2012: Multi-Versioning Android User Interfaces:
https://www.youtube.com/watch?v=amZM8oZBgfk
• Android Dashboards:
https://developer.android.com/about/dashboards/index.html
• Android Fragmentation visualized:
http://opensignal.com/reports/fragmentation-2013/

66. Questions?