Making Dogfood Builds Testable and Fun Eric Cochran Droidcon London October 27, 2017

Why? Build faster

Why? Build faster Force edge cases

Why? Build faster Force edge cases QA feature flags and A/B tests

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

How? Gradle build flavors

How? Gradle build flavors Dependency inversion

How? Gradle build flavors Dependency inversion Amazing libraries

How? Gradle build flavors Dependency inversion Amazing libraries Google Play private listing

Gradle buildTypes { debug { applicationIdSuffix 'debug' } } productFlavors { internal { applicationIdSuffix 'internal' } }

Gradle

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

Gradle internalImplementation 'com.example.debugging-library:logging:1.0.0' productionImplementation 'com.example.production-library:crash-reporting:1.0.0'

Gradle Build types for signing Flavors for changes

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

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; } }

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

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

Pushing down behavior controls in Android Views created with reflection class ServiceContextWrapper extends ContextWrapper { final String serviceName; final Object service; LayoutInflater inflater; @Override @Nullable 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); } }

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

Add controls for behavior src/internal/rest/layout/home_debug.xml

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

Practical Usage

A/B tests interface AbTestProvider { enum Transportation { TRAIN, PLANE, BOAT } boolean autoScroll(); Transportation 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 Transportation defaultTransportation() { return parseTransportation(firebaseRemoteConfigs.valueOf("transportation")); } }

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

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

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()); } }

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

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

Telescope https://github.com/mattprecious/telescope class HomeLayoutFactory implements ViewFactory { @Override public View create(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", "[email protected]")); return layout; } } src/internal/java

Telescope

Leak Canary Use RefWatcher everywhere and give the no-op source set to production. internalImplementation "com.squareup.leakcanary:leakcanary-android:$leakcanaryVersion" productionImplementation “com.squareup.leakcanary:leakcanary-android-no-op:$leakcanaryVersion” https://github.com/square/leakcanary

Leak Canary Use RefWatcher everywhere and give the no-op source set to production. internalImplementation "com.squareup.leakcanary:leakcanary-android:$leakcanaryVersion" productionImplementation “com.squareup.leakcanary:leakcanary-android-no-op:$leakcanaryVersion” Extend DisplayLeakService and post notifications remotely automatically. https://github.com/square/leakcanary

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

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

@Eric_Cochran github.com/NightlyNexus nightlynexus.com