Making Debug Builds Testable and Fun Eric Cochran MCE May 8, 2017

Why? - Build faster - Force edge cases - QA feature flags and A/B tests - Get actionable feedback from QA

3 How? - Grade build flavors - Dependency Inversion - Amazing libraries - Google Play private listing

Gradle buildTypes { debug { applicationIdSuffix ".debug" } release { signingConfig signingConfigs.release } } productFlavors { internal { applicationId 'com.example.internal' } production { applicationId 'com.example' } }

Gradle

Gradle sourceSets { internal { java.srcDirs = ['internal/java'] // array. res.srcDirs = ['internal/res'] // array. manifest.srcFile 'internal/AndroidManifest.xml' // single. } // etc. }

Gradle internalCompile 'com.example.debugging-library:logging:1.0.0' productionCompile 'com.example.production-library:crash-reporting:1.0.0'

Gradle Build types for signing Flavors for changes

9 Add controls for behavior Indirection interface Tweeter { void postTweet(); } class RealTweeter implements Tweeter { @Override public void postTweet() { // Post! } }

10 Add controls for behavior Indirection class LoggingTweeter implements Tweeter { final Tweeter delegate; final Logger logger; boolean log; @Override public void postTweet() { delegate.postTweet(); if (log) logger.logTweet(); } void log(boolean log) { this.log = log; } }

11 Add controls for behavior class DebugView { @Inject LoggingTweeter loggingTweeter; loggingTweeter.setOnCheckedChangeListener((buttonView, isChecked) -> { loggingTweeter.log(isChecked); } }

12 Dependency Inversion Zero-argument factory methods for every type. — Gregory Kick Control implementation and behavior from higher in the graph.

13 Pushing down behavior controls in Android Views created with reflection class ServiceContextWrapper extends ContextWrapper { final String serviceName; final Object service; LayoutInflater inflater; @Override public Object getSystemService(String name) { if (serviceName.equals(name)) { return service; } if (LAYOUT_INFLATER_SERVICE.equals(name)) { if (inflater == null) { inflater = LayoutInflater.from(getBaseContext()).cloneInContext(this); } return inflater; } return super.getSystemService(name); } }

14 Add controls for behavior class HomeLayoutFactory implements ViewFactory { @Override public View createView(Context context, ViewGroup parent) { LayoutInflater inflater = LayoutInflater.from(context); return inflater.inflate(R.layout.home_debug, parent, false); } } class HomeLayoutFactory implements ViewFactory { @Override public View createView(Context context, ViewGroup parent) { LayoutInflater inflater = LayoutInflater.from(context); return inflater.inflate(R.layout.home, parent, false); } } src/internal/java src/production/java

15 Add controls for behavior src/internal/res/layout/home_debug.xml DebugView.java setOnApplyWindowInsetsListener((v, insets) -> { // Do not consume insets. DebugView.this.onApplyWindowInsets(insets); return insets; });

16

17 Practical Usage

18 A/B tests interface AbTestProvider { enum TransportationType { TRAIN, PLANE, BOAT } boolean autoScroll(); TransportationType defaultTransportation(); } class InternalAbTestProvider implements AbTestProvider { // with getters and setters, modified by debug view. } class ProductionAbTestProvider implements AbTestProvider { @Override public boolean autoScroll() { return firebaseRemoteConfigs.valueOf("auto_scroll"); } @Override public TransportationType defaultTransportation() { return parseTransportationType(firebaseRemoteConfigs.valueOf("transportation")); } }

19 Rx-Preferences (SharedPreferences wrapper) interface Preference { interface Converter { @NonNull T deserialize(@NonNull String serialized); @NonNull String serialize(@NonNull T value); } @NonNull T get(); void set(@NonNull T value); boolean isSet(); void delete(); } https://github.com/f2prateek/rx-preferences/

20 Retrofit interface NamesService { @GET Call> names(@Url String url); } // Empty state. @AppScope @Provides static NamesService provideNamesService() { return url -> Calls.response(Collections.emptyList()); } https://github.com/square/retrofit/tree/master/retrofit-mock

21 OkHttp Interceptors class NoNetworkInterceptor implements Interceptor { volatile boolean noNetwork; void setNoNetwork(boolean noNetwork) { this.noNetwork = noNetwork; } @Override public Response intercept(Chain chain) throws IOException { if (noNetwork) { throw new IOException("You disabled the network!"); } return chain.proceed(chain.request()); } }

22 OkHttp Logging Interceptor https://github.com/square/okhttp/tree/master/okhttp-logging-interceptor @AppScope @Provides OkHttpClient provicesOkHttpClient(Cache cache) { return new OkHttpClient.Builder().cache(cache) .addInterceptor(new GzipRequestInterceptor()) // ... .addInterceptor(new HttpLoggingInterceptor()).build(); }

23 Telescope src/internal/res/layout/home_debug.xml https://github.com/mattprecious/telescope

24 Telescope class HomeLayoutFactory implements ViewFactory { @Override public View createView(Context context, ViewGroup parent) { LayoutInflater inflater = LayoutInflater.from(context); TelescopeLayout layout = (TelescopeLayout) inflater.inflate(R.layout.home_telescope, parent, false); layout.setLens(new EmailDeviceInfoLens(context, "Glitch", "eric@ifttt.com")); } } src/internal/java https://github.com/mattprecious/telescope

25 Telescope

26 Leak Canary Use RefWatcher everywhere and give the no-op source set to production. internalCompile "com.squareup.leakcanary:leakcanary-android:${leakCanaryVersion}" productionCompile "com.squareup.leakcanary:leakcanary-android-no-op:${leakCanaryVersion}" Extend DisplayLeakService and post notifications remotely automatically. https://github.com/square/leakcanary

27 Use Google Play! Auto updates! Pricing & Distribution section > Restrict Distribution https://support.google.com/a/answer/2494992 Publish!

28 Matt Precious Debug Builds: A New Hope https://youtu.be/Ae4vqz29W9U u2020 https://github.com/JakeWharton/u2020 Android Studio team! Open source projects creators! Credits

29 @Eric_Cochran github.com/NightlyNexus nightlynexus.com