Refactoring Plaid - A Reactive MVP Approach

by Hannes Dorfmann

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HELLO I’m Hannes

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REFACTORING PLAID A REACTIVE MVP APPROACH

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SLOWED DOWN BY BAD CODE?

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FEAR CHANGING CODE!

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FEAR CHANGING CODE!

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TDD Test-Driven-Development

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SOLID Robert C. Martins  „Uncle Bob“

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SINGLE RESPONSIBILITY “A class should only have one reason to change” Book   currentPage() nextPage() print()

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SINGLE RESPONSIBILITY “A class should only have one reason to change” Book   currentPage() nextPage() print() Book   currentPage() nextPage() Printer   print(Book)

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IMMUTABILITY

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You want an   immutable hot dog

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AUTOVALUE @AutoValue public abstract class HotDog { }

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AUTOVALUE @AutoValue public abstract class HotDog implements Parcelable { }

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AUTOVALUE @AutoValue public abstract class HotDog implements Parcelable {  @Json public abstract double getPrice(); }

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AUTOVALUE @AutoValue public abstract class HotDog implements Parcelable {  @Json public abstract double getPrice(); @ColumnName public abstract boolean hasKetchup(); }

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AUTOVALUE @AutoValue public abstract class HotDog implements Parcelable {  @Json public abstract double getPrice(); @ColumnName public abstract boolean hasKetchup(); public abstract static HotDog(double p, boolean k) { return new AutoValue_HotDog(p, k); } }

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MVC Model-View-Controller

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MVC Trygve Reenskaug View Model Controller observes changes

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PLAID Nick Butcher

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PLAID • https://github.com/nickbutcher/plaid • 5170 Stars on Github • Last commit: 1st of June 2016 • 5.000 - 10.000 installs 2nd June 2016

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PLAID • No clear Separation of responsibilities • AsyncTask • Android Services • Shared Preferences for persistency 2nd June 2016

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HomeActivity

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HomeActivity

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HomeActivity ConnectivityManager

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HomeActivity ConnectivityManager Animations

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HomeActivity ConnectivityManager Animations FeedAdapter

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HomeActivity ConnectivityManager Animations FilterAdapter FeedAdapter

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged()

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged()

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged()

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged()

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged()

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged() SourceManager

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged() SourceManager

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged() SourceManager

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REFACTORING

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Internet

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Mock

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https://www.getpostman.com/

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src/test/resources ClassLoader classLoader = getClass().getClassLoader(); File ﬁle = new File(classLoader.getResource("someﬁle.json").getFile());

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src/test/resources ClassLoader classLoader = getClass().getClassLoader(); File ﬁle = new File(classLoader.getResource("someﬁle.json").getFile()); Mock https://github.com/square/okhttp/tree/master/mockwebserver

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class HomeActivityTest {  @Rule MockWebServer server = new MockWebServer(); @Test public void showItems(){ server.enqueue( new MockResponse (…) ); onView( withId( R.id.recyclerView )) .check( matches( isDisplayed() ); onView(withId( R.id.recyclerView)) .check( new RecyclerViewItemCountAssertion(20) ) // test visibility of error and loading view }

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CLEAN ARCHITECTURE Entity Entity Entity Interactor  Presenter  View 

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CLEAN ARCHITECTURE Entity Entity Entity Interactor  Presenter  View  Break the Rules! https://publicobject.com/2016/04/20/deliberate-disobedience/ Jesse Wilson

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HomeActivity ConnectivityManager Animations onActivityResult() FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap FilterAdapter getFilters() registerFilterChanged() SourceManager

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HomeActivity Animations FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap SourceManager

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REACTIVE PROGRAMMING

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java.util.Observable

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SQLBrite SQLiteDatabase SourceDao

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interface SourceDao {    fun getAllSources(): Observable>    fun getEnabledSources(): Observable>    fun insert(source: Source): Observable    fun delete(source: Source): Observable }

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@AutoValue class Source : Parcelable {  @ColumnName(COL_NAME) fun name() : String @ColumnName(COL_ENABLED) fun boolean enabled(); }

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TDD • Write failing unit test ﬁrst • Write just enough code to pass all tests • Repeat

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class SqliteSourceDaoTest {  @Test fun insertAndGet(){ dao = SqliteSourceDao() val source = Source.create(…) val inserted = dao.insert(source)  .toBlocking().first() assertEquals(1, insertRes) } }

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Unit Test failed

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class SqliteSourceDao : SourceDao, Dao() {    fun insert(source: Source): Observable = insert(TABLE, source.toContentValues()) }

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Unit Tests OK

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Unit Test failed

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class SqliteSourceDao : SourceDao, Dao() {    fun insert(source: Source): Observable = insert(TABLE, source.toContentValues()) fun getAll(source: Source): Observable> = query( SELECT(“*“).FROM(TABLE) ) .mapToList(Source.MAPPER) }

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Unit Tests OK

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HomeActivity Animations FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap SourceManager

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HomeActivity Animations FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap SourceDao

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HomeActivity Animations FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap SourceDao

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HomeActivity Animations FilterAdapter FeedAdapter DataManager pageIndexMap runningCallsMap SourceDao

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RxBus

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RxBus

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HomeActivity Animations FilterAdapter FeedAdapter DataManager SourceDao P R E  S  E  N  T  E R  View Model

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TESTING MVP • View with Mock Presenter • Presenter with Mock View and Mock Model • Model plain old unit test (slides before)

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SINGLE RESPONSIBILITY DataManager pageIndexMap runningCallsMap SourceDao

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SINGLE RESPONSIBILITY DataManager pageIndexMap runningCallsMap SourceDao Route

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SINGLE RESPONSIBILITY DataManager pageIndexMap runningCallsMap SourceDao Route Queries Http Endpoint

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SINGLE RESPONSIBILITY DataManager pageIndexMap runningCallsMap SourceDao Route Router Queries Http Endpoint

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SINGLE RESPONSIBILITY DataManager pageIndexMap runningCallsMap SourceDao Route Router Queries Http Endpoint A collection of Routes

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SINGLE RESPONSIBILITY DataManager pageIndexMap runningCallsMap SourceDao Route Router Page Queries Http Endpoint A collection of Routes

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SINGLE RESPONSIBILITY DataManager pageIndexMap runningCallsMap SourceDao Route Router Page Queries Http Endpoint A collection of Routes Page Index

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OBSERVABLE STREAM SourceDao Route Router Page SQLBrite SQLiteDatabase

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