This document discusses the benefits of unit testing Android applications using Robolectric. It recommends writing tests first before coding using a test-driven development approach. Robolectric allows writing unit tests that run on the JVM rather than an emulator, speeding up test runs. The author's company Amplify uses Robolectric to unit test their Android apps, with over 4,500 tests across repositories. Migrating to the latest Robolectric version took 3 weeks but was worthwhile for increased testability. Other tools like RoboGuice, Mockito, and Android FEST are also used for testing.

1. The Magic of Android Unit Testing
Johny
Urgiles

2. Johny Urgiles
● 3 years @ Amplify
● Android dev for half of that
● Code quality aficionado
● The Lab for Robotics Education

4. Amplify & Test Driven Development
● Write test first
● See it fail
● Write simplest possible solution
● Refactor
● Sleep peacefully at night

5. Finished Product

6. Slow &
Careful

7. Slow &
Careful

8. Slow &
Careful
Fast &
Risky

9. Slow &
Careful
Fast &
Risky

11. Android & TDD
● Android Instrumentation Unit Testing
○ Pretty slow by unit test standards
○ We still have to maintain a
separate infrastructure for
tablet <-> tablet interaction

12. Android on JUnit

13. Stubbin

14. It’s Raining Runtime Exceptions

15. Robolectric 2.0
JVM
Robolectric
JUnit Test

17. Robolectric
● Mimics Android functionality
● 2.0 includes Android code (4.2.1 rc1)
● Provides view into Android internals
● Extendable with ‘Shadows’

18. Robolectric @ Amplify
● 4500 unit tests across our Android Apps
● Most in a single repo: 3751
○ Runs in 6.5 minutes (Macbook Pro)
○ Migration to Robolectric 2.0 took a part-time dev
about 3 weeks
○ Worth it
● Devs run unit tests in IntelliJ

19. Code Time

20. More Unit Testing @ Amplify
● RoboGuice
○ Based on Google Guice
○ Dependency injection for Android
● Mockito
○ Standard Java Mock library
● Android FEST
○ Assertion library by Square