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I see Continuous Improvement Oubai Abbasi and Ahmed El-Helw

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How do we know the stability of a given build?

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How do we maintain code quality as the team grows?

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How do we quickly find bugs before they make their way into production?

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How do we make builds available more widely?

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How do we uncover hidden changes in our apps?

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Why? • Maintain a stylistically consistent code base • Catch common bugs and design flaws early on • Encourage a test driven culture • Build trust in the code quality

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Static Analysis Tools Catching issues early

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“Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard.”

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“It automates the process of checking Java code to spare humans of this boring (but important) task. This makes it ideal for projects that want to enforce a coding standard.”

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package ae.droidcon.checkstyle; class Example { static int add(int first, int second) { return first + second; } }

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[ant:checkstyle] [WARN] ~/code/experimentation/src/ main/java/ae/droidcon/checkstyle/Example.java:5:1: Line contains a tab character. [FileTabCharacter]

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package ae.droidcon.checkstyle; public class Example< T> { }

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[ant:checkstyle] [WARN] ~/code/experimentation/src/ main/java/ae/droidcon/checkstyle/Example.java:3:32: GenericWhitespace '<' is followed by whitespace. [GenericWhitespace]

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package ae.droidcon.checkstyle; class Example { static void awesome (int a, int b) { System.out.println(a + ", " + b); } }

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[ant:checkstyle] [WARN] ~/code/experimentation/src/ main/java/ae/droidcon/checkstyle/Example.java:4:23: '(' is preceded with whitespace. [MethodParamPad]

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• Avoid import java.util.*; • Import order • Modifier order • Unnecessary parentheses Other Stylistic Issues

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“It can find class design problems, method design problems.”

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class Example { int useless(int value) { value *= 2; return value; } }

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[ant:checkstyle] [WARN] ~/code/experimentation/src/ main/java/ae/droidcon/checkstyle/Example.java:5:11: Assignment of parameter 'value' is not allowed. [ParameterAssignment]

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package ae.droidcon.checkstyle; class Example { void play() { int fantasy = 7; int offset = 0; System.out.println(fantasy + offset); offset += 3; System.out.println(fantasy + offset); } }

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[ant:checkstyle] [WARN] ~/code/experimentation/src/ main/java/ae/droidcon/checkstyle/Example.java:5:9: Variable 'fantasy' should be declared final. [FinalLocalVariable]

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package ae.droidcon.checkstyle; class Util { static void op() {} static void secondOp() {} }

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[ant:checkstyle] [WARN] ~/code/experimentation/src/ main/java/ae/droidcon/checkstyle/Util.java:3:1: Utility classes should not have a public or default constructor. [HideUtilityClassConstructor]

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Lint Photo by Andrew Neel on Unsplash

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object Caller { fun whoYouGonnaCall(context: Context) { val intent = Intent(Intent.ACTION_CALL, Uri.parse("tel:" + "GHOSTBUSTERS")) context.startActivity(intent) } }

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~/code/experiments/app/src/main/kotlin/ae/droidcon/ lint/Caller.kt:12: Error: Missing permissions required by intent Intent.ACTION_CALL: android.permission.CALL_PHONE [MissingPermission] context.startActivity(intent)

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class BoringActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.demo) val button: ImageButton = findViewById(R.id.button) button.setOnClickListener { } } }

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~/code/experiments/app/src/main/java/ae/droidcon/lint/ BoringActivity.kt:14: Error: Unexpected implicit cast to ImageButton: layout tag was Button [WrongViewCast] val button: ImageButton = findViewById(R.id.button)

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.demo) val button: Button = findViewById(R.id.button) button.setOnClickListener { } val drawable = ColorDrawable( R.color.accent_material_dark) button.background = drawable }

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~/code/experiments/app/src/main/java/ae/droidcon/ lint/BoringActivity.kt:20: Error: Call requires API level 16 (current min is 14): android.view.View#setBackground [NewApi] button.background = drawable

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~/code/experiments/app/src/main/java/ae/droidcon/ lint/BoringActivity.kt:19: Error: Should pass resolved color instead of resource id here: getResources().getColor(R.color.accent_material_dark) [ResourceAsColor] R.color.accent_material_dark)

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• WrongThread • LongLogTag • SQLiteString • … and many more Additional Checks

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Error Prone

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“Using Error Prone to augment the compiler’s type analysis, you can catch more mistakes before they cost you time, or end up as bugs in production.”

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public Collection sort(Collection foos) { Collections.sort(new ArrayList<>(foos)); return foos; }

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~/code/experimentation/src/main/java/ae/droidcon/ errorprone/Util.java:9: error: [UnusedCollectionModifiedInPlace] Collection is modified in place, but the result is not used Collections.sort(new ArrayList<>(foos)); ^ (see http://errorprone.info/bugpattern/ UnusedCollectionModifiedInPlace)

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public class Carbon { public SimpleDateFormat dating() { return new SimpleDateFormat("YYYY-MM-dd"); } }

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~/code/experimentation/src/main/java/ae/droidcon/ errorprone/Carb.java:7: error: [MisusedWeekYear] Use of "YYYY" (week year) in a date pattern without "ww" (week in year). You probably meant to use "yyyy" (year) instead. return new SimpleDateFormat("YYYY-MM-dd"); ^ (see http://errorprone.info/bugpattern/ MisusedWeekYear) Did you mean 'return new SimpleDateFormat("yyyy- MM-dd");'?

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public class Finder { public boolean findWaldo(Set values) { return (values.contains(1)); } }

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~/code/experimentation/src/main/java/ae/droidcon/ errorprone/Finder.java:7: error: [CollectionIncompatibleType] Argument '1' should not be passed to this method; its type int is not compatible with its collection's type argument Long return (values.contains(1)); ^ (see http://errorprone.info/bugpattern/ CollectionIncompatibleType)

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public class PostApocolypse { private final Set theLastOfUs = World.getRemainingHumans(); private volatile int zombies = 9001; public void fightZombies() { zombies--; } }

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~/code/experimentation/src/main/java/ae/droidcon/ errorprone/PostApocolypse.java:9: warning: [NonAtomicVolatileUpdate] This update of a volatile variable is non-atomic zombies--; ^ (see http://errorprone.info/bugpattern/ NonAtomicVolatileUpdate) 1 warning

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public String getFaction(int version) { String result; switch (version) { case FALLOUT_2: case FALLOUT_NEW_VEGAS: result = "New California Rangers"; break; case FALLOUT_3: result = "The Enclave"; break; case FALLOUT_4: result = "Institute"; default: result = "War never changes"; } return result; }

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~/code/experimentation/src/main/java/ae/droidcon/ errorprone/Fallout.java:17: warning: [FallThrough] Execution may fall through from the previous case; add a `// fall through` comment before this line if it was deliberate default: ^ (see http://errorprone.info/bugpattern/ FallThrough) 1 warning

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public class TemplarBase { protected Assassin ezio; public Creed getCreed() { return ezio.getCreed(); } } public class TemplarCastle extends TemplarBase { protected Assassin ezio; }

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public class TemplarBase { protected Assassin ezio; public Creed getCreed() { return ezio.getCreed(); } } public class TemplarCastle extends TemplarBase { protected Assassin ezio; }

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~/code/experimentation/src/main/java/ae/droidcon/ errorprone/TemplarCastle.java:4: warning: [HidingField] Hiding fields of superclasses may cause confusion and errors. This field is hiding a field of the same name in superclass: TemplarBase protected Assassin ezio; ^ (see http://errorprone.info/bugpattern/ HidingField) 1 warning

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• MissingOverride • ClassCanBeStatic • RemoveUnusedImports • SelfAssignment Additional Checks

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• InsecureCryptoUsage • FragmentInjection • UseBinds Security/Perf Checks

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Infer

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class Persona { private final Mementos mementos = new Mementos(); Shadow getShadowForPerson(String person) { if (mementos.hasShadowFor(person)) { return new Shadow(person); } return null; } void destroyShadow(String person) { final Shadow shadow = getShadowForPerson(person); shadow.unshadow(); } }

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class Persona { private final Mementos mementos = new Mementos(); Shadow getShadowForPerson(String person) { if (mementos.hasShadowFor(person)) { return new Shadow(person); } return null; } void destroyShadow(String person) { final Shadow shadow = getShadowForPerson(person); shadow.unshadow(); } }

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Found 1 issue Persona.java:13: error: NULL_DEREFERENCE object `shadow` last assigned on line 12 could be null and is dereferenced at line 13. 11. void destroyShadow(String person) { 12. final Shadow shadow = getShadowForPerson(person); 13. > shadow.unshadow(); 14. } 15. }

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• Context leaks • Resource leaks • Unsafe @GuardedBy access Additional Checks

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Testing

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How to UI test with network calls

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Hitting the real APIs • Unreliable • Can’t test edge cases • How to test payment related scenarios

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Hitting the real APIs • Unreliable • Can’t test edge cases • How to test payment related scenarios

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Building a mock interface •Reliable •Requires more coding, maintenance and testing

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Building a mock interface •Reliable •Requires more coding, maintenance and testing

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Mock web server •No extra code •Still hard to maintain and prepare

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class RecordCallsInterceptor constructor(context: Context, val gson: Gson) : Interceptor { ... override fun intercept(chain: Interceptor.Chain): Response { val request = chain.request() val response = chain.proceed(request) ... val recordModel = ApiRecordModel( request = ApiRecordRequestModel( path = request.url().encodedPath(), method = request.method(), headers = requestHeaders, body = requestBody ), response = ApiRecordResponseModel( code = response.code(), headers = responseHeaders, body = responseBody ) ) ... dumpToServer(recordModel) return response } }

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class RecordCallsInterceptor constructor(context: Context, val gson: Gson) : Interceptor { ... override fun intercept(chain: Interceptor.Chain): Response { val request = chain.request() val response = chain.proceed(request) ... val recordModel = ApiRecordModel( request = ApiRecordRequestModel( path = request.url().encodedPath(), method = request.method(), headers = requestHeaders, body = requestBody ), response = ApiRecordResponseModel( code = response.code(), headers = responseHeaders, body = responseBody ) ) ... dumpToServer(recordModel) return response } }

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class RecordCallsInterceptor constructor(context: Context, val gson: Gson) : Interceptor { ... override fun intercept(chain: Interceptor.Chain): Response { val request = chain.request() val response = chain.proceed(request) ... val recordModel = ApiRecordModel( request = ApiRecordRequestModel( path = request.url().encodedPath(), method = request.method(), headers = requestHeaders, body = requestBody ), response = ApiRecordResponseModel( code = response.code(), headers = responseHeaders, body = responseBody ) ) ... dumpToServer(recordModel) return response } }

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class RecordCallsInterceptor constructor(context: Context, val gson: Gson) : Interceptor { ... override fun intercept(chain: Interceptor.Chain): Response { val request = chain.request() val response = chain.proceed(request) ... val recordModel = ApiRecordModel( request = ApiRecordRequestModel( path = request.url().encodedPath(), method = request.method(), headers = requestHeaders, body = requestBody ), response = ApiRecordResponseModel( code = response.code(), headers = responseHeaders, body = responseBody ) ) ... dumpToServer(recordModel) return response } }

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class RecordCallsInterceptor constructor(context: Context, val gson: Gson) : Interceptor { ... override fun intercept(chain: Interceptor.Chain): Response { val request = chain.request() val response = chain.proceed(request) ... val recordModel = ApiRecordModel( request = ApiRecordRequestModel( path = request.url().encodedPath(), method = request.method(), headers = requestHeaders, body = requestBody ), response = ApiRecordResponseModel( code = response.code(), headers = responseHeaders, body = responseBody ) ) ... dumpToServer(recordModel) return response } }

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What do we do with dumped requests?

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We save them as a Postman Collection

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We save them as a Postman Collection • Nice GUI • Easy to edit responses and search requests • Supports placeholders for path, headers or body

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Now what?

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@Test public void loginTest_success() { mount("defaultCollection"); onView(withId(R.id.email)).perform(typeText("[email protected]")); onView(withId(R.id.edt_password)).perform(typeText("Password"), closeSoftKeyboard()); onView(withId(R.id.btn_login_with_fb)).perform(click()); }

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@Test public void loginTest_success() { mount("defaultCollection"); onView(withId(R.id.email)).perform(typeText("[email protected]")); onView(withId(R.id.password)).perform(typeText("Password"), closeSoftKeyboard()); onView(withId(R.id.btn_login)).perform(click()); }

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@Test public void loginTest_success() { mount("defaultCollection"); onView(withId(R.id.email)).perform(typeText("[email protected]")); onView(withId(R.id.edt_password)).perform(typeText("Password"), closeSoftKeyboard()); onView(withId(R.id.btn_login_with_fb)).perform(click()); }

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fun mount(collectionName: String, fileName: String) { cachedCollections[collectionName] = file.item.firstOrNull { collection -> collection.name==collectionName }?: throw IllegalArgumentException("Collection not found: $collectionName") }

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fun mount(collectionName: String, fileName: String) { val file = PostmanLoader.load(fileName) cachedCollections[collectionName] = file.item.firstOrNull { collection -> collection.name == collectionName }?: throw IllegalArgumentException("Collection not found: $collectionName") }

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fun mount(collectionName: String, fileName: String) { val file = PostmanLoader.load(fileName) cachedCollections[collectionName] = file.item.firstOrNull { collection -> collection.name == collectionName }?: throw IllegalArgumentException("Collection not found: $collectionName") }

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MockWebServer().apply { setDispatcher(object : Dispatcher() { override fun dispatch(request: RecordedRequest): MockResponse { return mountedCollections .firstOrNull { requestsMatch(request, it.request) }?.let { createResponseFromPostman(it.response[0]) } ?: MockResponse().apply { setResponseCode(404) } } })

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MockWebServer().apply { setDispatcher(object : Dispatcher() { override fun dispatch(request: RecordedRequest): MockResponse { return mountedCollections .firstOrNull { requestsMatch(request, it.request) }?.let { createResponseFromPostman(it.response[0]) } ?: MockResponse().apply { setResponseCode(404) } } })

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MockWebServer().apply { setDispatcher(object : Dispatcher() { override fun dispatch(request: RecordedRequest): MockResponse { return mountedCollections .firstOrNull { requestsMatch(request, it.request) }?.let { createResponseFromPostman(it.response[0]) } ?: MockResponse().apply { setResponseCode(404) } } })

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MockWebServer().apply { setDispatcher(object : Dispatcher() { override fun dispatch(request: RecordedRequest): MockResponse { return mountedCollections .firstOrNull { requestsMatch(request, it.request) }?.let { createResponseFromPostman(it.response[0]) } ?: MockResponse().apply { setResponseCode(404) } } })

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How to confirm the UI looks right?

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@Test public void loginTest_success() { mount("defaultCollection"); screenshot("loginTest", "success", "emptyFields", lang); onView(withId(R.id.email)).perform(typeText("[email protected]")); onView(withId(R.id.edt_password)).perform(typeText("Password"), closeSoftKeyboard()); screenshot("loginTest", "success", "filledFields", lang); onView(withId(R.id.btn_login_with_fb)).perform(click()); screenshot("loginTest", "success", "loading", lang); }

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@Test public void loginTest_success() { mount("defaultCollection"); screenshot("loginTest", "success", "emptyFields", lang); onView(withId(R.id.email)).perform(typeText("[email protected]")); onView(withId(R.id.edt_password)).perform(typeText("Password"), closeSoftKeyboard()); screenshot("loginTest", "success", "filledFields", lang); onView(withId(R.id.btn_login_with_fb)).perform(click()); screenshot("loginTest", "success", "loading", lang); }

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What to do with screenshot? • Upload them to your server • Tag them with configuration, test, scenario, date • Run image diffing (ie: http://www.imagemagick.org/ Usage/compare/) • Flag different/new screenshots for manual verification

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Making it cross platform • Share API data • Run a python mock server instead of OkHttp • Share screenshot diff-ing logic/UI

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Hidden Changes

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Photo from LifeWithCats

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Permissions

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aapt d permissions ./app/build/outputs/apk/debug/app-debug.apk uses-permission: name='android.permission.INTERNET' uses-permission: name='android.permission.WRITE_EXTERNAL_STORAGE' uses-permission: name='android.permission.ACCESS_NETWORK_STATE' uses-permission: name='android.permission.WAKE_LOCK' uses-permission: name='android.permission.READ_EXTERNAL_STORAGE'

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dependencies { implementation deps.helpbug.helpbug // more dependencies }

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aapt d permissions ./app/build/outputs/apk/debug/app-debug.apk

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› diff before after 6a7,9 > uses-permission: name='android.permission.ACCESS_WIFI_STATE' > uses-permission: name='android.permission.RECORD_AUDIO' > uses-permission: name='android.permission.MODIFY_AUDIO_SETTINGS' Picture from principedifino

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Method Count

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> Task :app:countDebugDexMethods Total methods in app-debug.apk: 52673 (80.37% used) Total fields in app-debug.apk: 30053 (45.86% used) Total classes in app-debug.apk: 6962 (10.62% used) Methods remaining in app-debug.apk: 12862 Fields remaining in app-debug.apk: 35482 Classes remaining in app-debug.apk: 58573

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dependencies { implementation deps.helpbug.helpbug // more dependencies }

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> Task :app:countDebugDexMethods Total methods in app-debug.apk: 69802 (106.51% used) Total fields in app-debug.apk: 42438 (64.76% used) Total classes in app-debug.apk: 9291 (14.18% used) Methods remaining in app-debug.apk: 0 Fields remaining in app-debug.apk: 23097 Classes remaining in app-debug.apk: 56244

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Delta methods: +17129 Delta fields: +12385 Delta classes: +2329

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APK Size

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What else can we do? •Upload apk to S3 bucket for internal distribution •Automatically upload builds to Google Play •Post on slack about new builds

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lane :alpha do gradle(task: "clean assembleDebug test android") aws_s3 slack({ message: "new version uploaded to S3", channel: “#qa" }) end

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lane :alpha do gradle(task: "clean assembleDebug test android") aws_s3 slack({ message: "new version uploaded to S3", channel: “#qa" }) end

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lane :alpha do gradle(task: "clean assembleDebug test android") aws_s3 slack({ message: "new version uploaded to S3", channel: “#qa" }) end

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lane :alpha do gradle(task: "clean assembleDebug test android") aws_s3 slack({ message: "new version uploaded to S3", channel: “#qa" }) end

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lane :alpha do gradle(task: "clean assembleDebug test android") aws_s3 slack({ message: "new version uploaded to S3", channel: “#qa" }) end

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lane :release do gradle(task: "clean assembleRelease test android") supply slack({ message: "new version released", channel: “#announcements" }) end

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lane :release do gradle(task: "clean assembleRelease test android") supply slack({ message: "new version released", channel: “#announcements" }) end

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Code Coverage

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Photo by Robert Zunikoff on Unsplash

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Photo by Annie Spratt on Unsplash Where?

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Compilation time Pull request time Commit time Post-commit time Photo by Ales Krivec on Unsplash

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Photo by Evan Kirby on Unsplash Gotchas • Flaky Tests • Tool version updates • Unstable environment • Crashing tests

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Test Orchestrator

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• Invest in improving build times • Set up static analysis tools • Optimize for code quality and stability Summary

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Photo by Bryan Minear on Unsplash

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References • https://speakerdeck.com/kaskasi/i-am-on-a-fastlane-to-hell • https://medium.com/square-corner-blog/surfacing-hidden- change-to-pull-requests-6a371266e479 • https://github.com/KeepSafe/dexcount-gradle-plugin • https://github.com/JakeWharton/dex-method-list • http://www.imagemagick.org/Usage/compare/ • https://android.github.io/kotlin-guides/interop.html