About Robolectric, PowerMock and JaCoCo At Android Taipei on 2015/12/23

1. Robolectric
Test Android on the JVM

2. HELLO!
I am Richard Chang
Android Engineer in HTC, Movial and VMFive
You can find me via chiel99 AT gmail.com

3. Outline
● Challenges of Android unit test
● Robolectric
● PowerMock
● JaCoCo
● Reference

4. Challenges of
Android unit test

5. 1. java.lang.RuntimeException(“Stub!”)
Google removed the method body in android.jar

6. 2. Mock everything
Mock framework is great!
But mocking every Android framework object exhausts
programmers

7. 3. On Real Device or Emulator
Impact your Continueous Integration (CI) process
SLOW, SLOW, SLOW

8. Robolectric

9. What is Robolectric?
● An Android unit test framework that let you run your tests on
regular JVM
● Start from Xtreme Labs (Acquired by Pivotal Labs)
● Open source

10. Why Robolectric?
● Fast
● Run on JVM instead of Dalvik/ART
○ No dexing, packaging, signing, deploying...
● Well handled the resources/layout xmls emulation
○ findViewById(R.id.text)
● Can be collaborated with other mock frameworks
○ Mockito, PowerMock...

11. How it works?
● Shadow objects
○ Robolectric replaces Android classes so-called Shadows
● Robolectric intercepts the loading of Android classes during testing
Android
ImageView
Test code
Shadow
ImageView
mImgView.getImageBitmap getImageBitmap
return Bitmapreturn Bitmap

12. Shadows

13. How to use Robolectric?
● Build.gradle
○ dependencies: testCompile "org.robolectric:robolectric:3.0"
● Create test folder: PROJECT/app/src/test/java/...

14. How to use Robolectric?
● @RunWith(RobolectricGradleTestRunner.class)
● @Config(constants = BuildConfig.class)
● @Config(sdk = Build.VERSION_CODES.KITKAT)
● @Config(manifest = “some-path/AndroidManifest.xml”)
● @Config(qualifiers = “en-port-hdpi”)
● ./gradlew testDebug
● ./gradlew testDebug --tests=”*.TestClassName”

15. Demo

16. Drawbacks
● Can not follow the latest Android version
○ Robolectric 3.0 supports API 21 (Lollipop) - 2015 August
● Can not cover OEM implementation
○ Still need real devices for integration tests
● Still have bugs
○ Please report or improve it

17. PowerMock

18. What is PowerMock?
● Mock framework extends on EasyMock and Mockito
● To enable mocking on:
○ constructors
○ static methods
○ final classes and methods
○ private methods
● Sorry, can not run on Dalvik VM
○ Thanks again for Robolectric

19. How to use PowerMock?
● Build.gradle
dependencies {
testCompile "org.powermock:powermock-module-junit4:1.6.1"
testCompile "org.powermock:powermock-module-junit4-rule:1.6.1"
testCompile "org.powermock:powermock-classloading-xstream:1.6.1"
testCompile "org.powermock:powermock-api-mockito:1.6.1"
}

20. How to use PowerMock?
● @PrepareForTest(ClassName.class)
● constructor: whenNew()
● static method: mockStatic() or stub()
● final or private methods: spy()
● private member: WhiteBox.setInternalState()

21. Demo

22. JaCoCo

23. A story about one
million dollars

24. What is Jacoco?
● Java Code Coverage Library
● Line and branch coverage
● Without injecting code inside your project
● Good integration with CI tools like Jenkins
● Benefits:
○ Confidence for Team
○ Happiness for Boss
○ Avoid writing duplicated test code

25. How to use JaCoCo?
● build.gradle
○ apply jacoco plugin
○ setup jacoco toolVersion
○ add JacocoReport task and depends on testDebug
○ setup report format (xml, html, csv)
● Run test with jacoco
○ ./gradlew clean jacocoTestReportTask

26. Demo

27. Thanks!
Any questions?
You can find the sample code on github:
https://github.com/chiel99/robolectricDemo

28. VMFive is hiring!
● Android Engineer
● Backend Engineer (Node.js or Python)
● Cloud Engineer in Operation
● Cloud Engineer in Test
● Taiwan Businese Development
● Data Scientist
● Campaign Testing
http://vmfive.com

29. Reference
● http://robolectric.org/
● https://github.com/robolectric/robolectric
● http://www.slideshare.net/joemoore1/droidconuk-tdd-android-
with-robolectric
● https://github.com/jayway/powermock
● http://eclemma.org/jacoco/index.html