Merge pull request ReactiveX#458 from soundcloud/android-ui-component…

…-operator

[rxjava-android] OperationObserveFromAndroidComponent

rxjava-contrib/rxjava-android/build.gradle

@@ -2,10 +2,13 @@ apply plugin: 'osgi'
 
 dependencies {
     compile project(':rxjava-core')
+    provided 'com.google.android:android:4.0.1.2'
+    provided 'com.google.android:support-v4:r7'
+
+    // testing
     provided 'junit:junit-dep:4.10'
     provided 'org.mockito:mockito-core:1.8.5'
     provided 'org.robolectric:robolectric:2.1.1'
-    provided 'com.google.android:android:4.0.1.2'
 }
 
 javadoc {

rxjava-contrib/rxjava-android/src/main/java/rx/android/observables/AndroidObservable.java

@@ -0,0 +1,25 @@
+package rx.android.observables;
+
+import rx.Observable;
+import rx.operators.OperationObserveFromAndroidComponent;
+
+import android.app.Activity;
+import android.app.Fragment;
+
+public final class AndroidObservable {
+
+    private AndroidObservable() {}
+
+    public static <T> Observable<T> fromActivity(Activity activity, Observable<T> sourceObservable) {
+        return OperationObserveFromAndroidComponent.observeFromAndroidComponent(sourceObservable, activity);
+    }
+
+    public static <T> Observable<T> fromFragment(Fragment fragment, Observable<T> sourceObservable) {
+        return OperationObserveFromAndroidComponent.observeFromAndroidComponent(sourceObservable, fragment);
+    }
+
+    public static <T> Observable<T> fromFragment(android.support.v4.app.Fragment fragment, Observable<T> sourceObservable) {
+        return OperationObserveFromAndroidComponent.observeFromAndroidComponent(sourceObservable, fragment);
+    }
+
+}

rxjava-contrib/rxjava-android/src/main/java/rx/operators/OperationObserveFromAndroidComponent.java

@@ -0,0 +1,298 @@
+package rx.operators;
+
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyInt;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+import rx.Observable;
+import rx.Observer;
+import rx.Subscription;
+import rx.android.concurrency.AndroidSchedulers;
+import rx.subjects.PublishSubject;
+
+import android.app.Activity;
+import android.app.Fragment;
+import android.os.Looper;
+import android.util.Log;
+
+import java.lang.reflect.Field;
+import java.util.concurrent.Callable;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+public class OperationObserveFromAndroidComponent {
+
+    public static <T> Observable<T> observeFromAndroidComponent(Observable<T> source, android.app.Fragment fragment) {
+        return Observable.create(new OnSubscribeFragment<T>(source, fragment));
+    }
+
+    public static <T> Observable<T> observeFromAndroidComponent(Observable<T> source, android.support.v4.app.Fragment fragment) {
+        return Observable.create(new OnSubscribeSupportFragment<T>(source, fragment));
+    }
+
+    public static <T> Observable<T> observeFromAndroidComponent(Observable<T> source, Activity activity) {
+        return Observable.create(new OnSubscribeBase<T, Activity>(source, activity));
+    }
+
+    private static class OnSubscribeBase<T, AndroidComponent> implements Observable.OnSubscribeFunc<T> {
+
+        private static final String LOG_TAG = "AndroidObserver";
+
+        private final Observable<T> source;
+        private AndroidComponent componentRef;
+        private Observer<? super T> observerRef;
+
+        private OnSubscribeBase(Observable<T> source, AndroidComponent component) {
+            this.source = source;
+            this.componentRef = component;
+        }
+
+        private void log(String message) {
+            if (Log.isLoggable(LOG_TAG, Log.DEBUG)) {
+                Log.d(LOG_TAG, "componentRef = " + componentRef);
+                Log.d(LOG_TAG, "observerRef = " + observerRef);
+                Log.d(LOG_TAG, message);
+            }
+        }
+
+        protected boolean isComponentValid(AndroidComponent component) {
+            return true;
+        }
+
+        @Override
+        public Subscription onSubscribe(Observer<? super T> observer) {
+            assertUiThread();
+            observerRef = observer;
+            final Subscription sourceSub = source.observeOn(AndroidSchedulers.mainThread()).subscribe(new Observer<T>() {
+                @Override
+                public void onCompleted() {
+                    if (componentRef != null && isComponentValid(componentRef)) {
+                        observerRef.onCompleted();
+                    } else {
+                        log("onComplete: target component released or detached; dropping message");
+                    }
+                }
+
+                @Override
+                public void onError(Throwable e) {
+                    if (componentRef != null && isComponentValid(componentRef)) {
+                        observerRef.onError(e);
+                    } else {
+                        log("onError: target component released or detached; dropping message");
+                    }
+                }
+
+                @Override
+                public void onNext(T args) {
+                    if (componentRef != null && isComponentValid(componentRef)) {
+                        observerRef.onNext(args);
+                    } else {
+                        log("onNext: target component released or detached; dropping message");
+                    }
+                }
+            });
+            return new Subscription() {
+                @Override
+                public void unsubscribe() {
+                    log("unsubscribing from source sequence");
+                    releaseReferences();
+                    sourceSub.unsubscribe();
+                }
+            };
+        }
+
+        private void releaseReferences() {
+            observerRef = null;
+            componentRef = null;
+        }
+
+        private void assertUiThread() {
+            if (Looper.getMainLooper() != Looper.myLooper()) {
+                throw new IllegalStateException("Observers must subscribe from the main UI thread, but was " + Thread.currentThread());
+            }
+        }
+    }
+
+    private static final class OnSubscribeFragment<T> extends OnSubscribeBase<T, android.app.Fragment> {
+
+        private OnSubscribeFragment(Observable<T> source, android.app.Fragment fragment) {
+            super(source, fragment);
+        }
+
+        @Override
+        protected boolean isComponentValid(android.app.Fragment fragment) {
+            return fragment.isAdded();
+        }
+    }
+
+    private static final class OnSubscribeSupportFragment<T> extends OnSubscribeBase<T, android.support.v4.app.Fragment> {
+
+        private OnSubscribeSupportFragment(Observable<T> source, android.support.v4.app.Fragment fragment) {
+            super(source, fragment);
+        }
+
+        @Override
+        protected boolean isComponentValid(android.support.v4.app.Fragment fragment) {
+            return fragment.isAdded();
+        }
+    }
+
+    @RunWith(RobolectricTestRunner.class)
+    @Config(manifest = Config.NONE)
+    public static final class UnitTest {
+
+        @Mock
+        private Observer<Integer> mockObserver;
+
+        @Mock
+        private Fragment mockFragment;
+
+        @Mock
+        private Activity mockActivity;
+
+        @Mock
+        private Observable<Integer> mockObservable;
+
+        @Before
+        public void setupMocks() {
+            MockitoAnnotations.initMocks(this);
+            when(mockFragment.isAdded()).thenReturn(true);
+        }
+
+        @Test
+        public void itThrowsIfObserverSubscribesFromBackgroundThread() throws Exception {
+            final Future<Object> future = Executors.newSingleThreadExecutor().submit(new Callable<Object>() {
+                @Override
+                public Object call() throws Exception {
+                    OperationObserveFromAndroidComponent.observeFromAndroidComponent(
+                            mockObservable, mockFragment).subscribe(mockObserver);
+                    return null;
+                }
+            });
+            future.get(1, TimeUnit.SECONDS);
+            verify(mockObserver).onError(any(IllegalStateException.class));
+            verifyNoMoreInteractions(mockObserver);
+        }
+
+        @Test
+        public void itObservesTheSourceSequenceOnTheMainUIThread() {
+            OperationObserveFromAndroidComponent.observeFromAndroidComponent(mockObservable, mockFragment).subscribe(mockObserver);
+            verify(mockObservable).observeOn(AndroidSchedulers.mainThread());
+        }
+
+        @Test
+        public void itForwardsOnNextOnCompletedSequenceToTargetObserver() {
+            Observable<Integer> source = Observable.from(1, 2, 3);
+            OperationObserveFromAndroidComponent.observeFromAndroidComponent(source, mockFragment).subscribe(mockObserver);
+            verify(mockObserver, times(3)).onNext(anyInt());
+            verify(mockObserver).onCompleted();
+            verify(mockObserver, never()).onError(any(Exception.class));
+        }
+
+        @Test
+        public void itForwardsOnErrorToTargetObserver() {
+            final Exception exception = new Exception();
+            Observable<Integer> source = Observable.error(exception);
+            OperationObserveFromAndroidComponent.observeFromAndroidComponent(source, mockFragment).subscribe(mockObserver);
+            verify(mockObserver).onError(exception);
+            verify(mockObserver, never()).onNext(anyInt());
+            verify(mockObserver, never()).onCompleted();
+        }
+
+        @Test
+        public void itDropsOnNextOnCompletedSequenceIfTargetComponentIsGone() throws Throwable {
+            PublishSubject<Integer> source = PublishSubject.create();
+
+            final OnSubscribeFragment<Integer> operator = new OnSubscribeFragment<Integer>(source, mockFragment);
+            operator.onSubscribe(mockObserver);
+
+            source.onNext(1);
+            releaseComponentRef(operator);
+
+            source.onNext(2);
+            source.onNext(3);
+            source.onCompleted();
+
+            verify(mockObserver).onNext(1);
+            verifyNoMoreInteractions(mockObserver);
+        }
+
+        @Test
+        public void itDropsOnErrorIfTargetComponentIsGone() throws Throwable {
+            PublishSubject<Integer> source = PublishSubject.create();
+
+            final OnSubscribeFragment<Integer> operator = new OnSubscribeFragment<Integer>(source, mockFragment);
+            operator.onSubscribe(mockObserver);
+
+            source.onNext(1);
+            releaseComponentRef(operator);
+
+            source.onError(new Exception());
+
+            verify(mockObserver).onNext(1);
+            verifyNoMoreInteractions(mockObserver);
+        }
+
+        private void releaseComponentRef(OnSubscribeFragment<Integer> operator) throws NoSuchFieldException, IllegalAccessException {
+            final Field componentRef = operator.getClass().getSuperclass().getDeclaredField("componentRef");
+            componentRef.setAccessible(true);
+            componentRef.set(operator, null);
+        }
+
+        @Test
+        public void itDoesNotForwardOnNextOnCompletedSequenceIfFragmentIsDetached() {
+            PublishSubject<Integer> source = PublishSubject.create();
+            OperationObserveFromAndroidComponent.observeFromAndroidComponent(source, mockFragment).subscribe(mockObserver);
+
+            source.onNext(1);
+
+            when(mockFragment.isAdded()).thenReturn(false);
+            source.onNext(2);
+            source.onNext(3);
+            source.onCompleted();
+
+            verify(mockObserver).onNext(1);
+            verify(mockObserver, never()).onCompleted();
+        }
+
+        @Test
+        public void itDoesNotForwardOnErrorIfFragmentIsDetached() {
+            PublishSubject<Integer> source = PublishSubject.create();
+            OperationObserveFromAndroidComponent.observeFromAndroidComponent(source, mockFragment).subscribe(mockObserver);
+
+            source.onNext(1);
+
+            when(mockFragment.isAdded()).thenReturn(false);
+            source.onError(new Exception());
+
+            verify(mockObserver).onNext(1);
+            verify(mockObserver, never()).onError(any(Exception.class));
+        }
+
+        @Test
+        public void itUnsubscribesFromTheSourceSequence() {
+            Subscription underlying = mock(Subscription.class);
+            when(mockObservable.observeOn(AndroidSchedulers.mainThread())).thenReturn(mockObservable);
+            when(mockObservable.subscribe(any(Observer.class))).thenReturn(underlying);
+
+            Subscription sub = OperationObserveFromAndroidComponent.observeFromAndroidComponent(
+                    mockObservable, mockActivity).subscribe(mockObserver);
+            sub.unsubscribe();
+
+            verify(underlying).unsubscribe();
+        }
+    }
+}