Droidcon 2013: Boundbox & Memento + Annotation Processing

Stéphane Nicolas, Octo Technology

Matthias Käppler, Soundcloud @mttkay

boundbox

Slides available online

https://github.com/stephanenicolas/boundbox

• break encapsulation to ease testing (with Android in mind)
• let’s you access things from Android SDK that you wouldn’t normally access
• also lets you add fields (e.g. for stub Android jars that only have methods available)
• can indicate how far up the hierarchy you want to expose
• don’t need to change your code — just adjust your tests
• access using reflection, but access checked at compile time
• open source on github
• compares with WhiteBox from PowerMock
• intended for helping test UI layer
  • find views by field name
  • invoke methods & inner classes directly
  • faster and more direct than robotium & UIAutomator
  • as fast as espresso

memento

https://github.com/mttkay/memento

• dealing with keeping state when the screen rotates
• the activity gets destroyed and recreated and all your state is thrown away…
• can use onRetainNonConfigurationInstance to pass objects through configuration changes
  • but what if you need to retain more than one object
  • deprecated in place of fragments — these keep their configuration using setRetainInstance
  • but watch out: setRetainInstance doesn’t work for child fragments and is super-prone for data leaks
• but what if you have multiple fragments sharing the same state?
• mark a package private field as @Retain
• override the new onLaunch method (used to indicate first time initialisation of the class i.e. not after a config change)
• then use Memento.retain(this)

annotation processing in general

• use JavaWriter from squareup
• look at how square does it for dagger dependency injection
• Google has a library so you can assert over java source files
  • lets you compile with a processor and check the output
• want to split up the annotation processor into two:
  • one for the client-side annotation itself and any required classes
  • one for the processor (don’t want it in your app)