Add bindView implementation and tests

build.gradle

@@ -20,8 +20,9 @@ ext {
 
     // Define all dependencies in the base project, to unify & make it easy to update
     rxJava = 'io.reactivex:rxjava:1.0.14'
+    rxBinding = 'com.jakewharton.rxbinding:rxbinding:0.2.0'
     appCompat = 'com.android.support:appcompat-v7:23.0.0'
     junit = 'junit:junit:4.12'
     mockito = 'org.mockito:mockito-core:1.10.19'
     robolectric = 'org.robolectric:robolectric:3.0'
-}
+}

rxlifecycle/build.gradle

@@ -15,6 +15,7 @@ repositories {
 
 dependencies {
     compile rootProject.ext.rxJava
+    compile rootProject.ext.rxBinding
 
     testCompile rootProject.ext.junit
     testCompile rootProject.ext.mockito

rxlifecycle/src/main/java/com/trello/rxlifecycle/RxLifecycle.java

@@ -14,6 +14,11 @@
 
 package com.trello.rxlifecycle;
 
+import android.view.View;
+
+import com.jakewharton.rxbinding.view.RxView;
+import com.jakewharton.rxbinding.view.ViewAttachEvent;
+
 import rx.Observable;
 import rx.functions.Func1;
 import rx.functions.Func2;
@@ -135,6 +140,57 @@ public static <T> Observable.Transformer<T, T> bindFragment(Observable<FragmentE
         return bind(lifecycle, FRAGMENT_LIFECYCLE);
     }
 
+    /**
+     * Binds the given source a View lifecycle.
+     * <p>
+     * Use with {@link Observable#compose(Observable.Transformer)}:
+     * {@code source.compose(RxLifecycle.bindView(lifecycle)).subscribe()}
+     * <p>
+     * This helper automatically determines (based on the lifecycle sequence itself) when the source
+     * should stop emitting items. For views, this effectively means watching for a detach event and
+     * unsubscribing the sequence when one occurs.
+     * <p>
+     * Note that this will unsubscribe after the first {@link ViewAttachEvent.Kind#DETACH} event is received,
+     * and will not resume if the view is re-attached later.
+     *
+     * @param view the view to bind the source sequence to
+     * @return a reusable {@link Observable.Transformer} that unsubscribes the source during the View lifecycle
+     */
+    public static <T> Observable.Transformer<T, T> bindView(final View view) {
+        if (view == null) {
+            throw new IllegalArgumentException("View must be given");
+        }
+
+        return bindView(RxView.detaches(view));
+    }
+
+    /**
+     * Binds the given source a View lifecycle.
+     * <p>
+     * Use with {@link Observable#compose(Observable.Transformer)}:
+     * {@code source.compose(RxLifecycle.bindView(lifecycle)).subscribe()}
+     * <p>
+     * This helper automatically determines (based on the lifecycle sequence itself) when the source
+     * should stop emitting items. For views, this effectively means watching for a detach event and
+     * unsubscribing the sequence when one occurs. Note that this assumes <em>any</em> event
+     * emitted by the given lifecycle indicates a detach event.
+     *
+     * @param lifecycle the lifecycle sequence of a View
+     * @return a reusable {@link Observable.Transformer} that unsubscribes the source during the View lifecycle
+     */
+    public static <T, E> Observable.Transformer<T, T> bindView(final Observable<E> lifecycle) {
+        if (lifecycle == null) {
+            throw new IllegalArgumentException("Lifecycle must be given");
+        }
+
+        return new Observable.Transformer<T, T>() {
+            @Override
+            public Observable<T> call(Observable<T> source) {
+                return source.takeUntil(lifecycle);
+            }
+        };
+    }
+
     private static <T, R> Observable.Transformer<T, T> bind(Observable<R> lifecycle,
                                                             final Func1<R, R> correspondingEvents) {
         if (lifecycle == null) {

rxlifecycle/src/test/java/com/trello/rxlifecycle/RxLifecycleTest.java

@@ -14,17 +14,27 @@
 
 package com.trello.rxlifecycle;
 
+import android.app.Activity;
+import android.view.View;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.robolectric.Robolectric;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
+
+import java.util.concurrent.CopyOnWriteArrayList;
+
 import rx.Observable;
+import rx.Subscription;
 import rx.observers.TestSubscriber;
 import rx.subjects.BehaviorSubject;
 import rx.subjects.PublishSubject;
 
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 
 @RunWith(RobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
@@ -225,4 +235,50 @@ public void testThrowsExceptionOutsideFragmentLifecycle() {
         observable.compose(RxLifecycle.bindFragment(lifecycle)).subscribe(testSubscriber);
         testSubscriber.assertError(IllegalStateException.class);
     }
+
+    @Test
+    public void testBindViewLifecycle() {
+        BehaviorSubject<Object> lifecycle = BehaviorSubject.create();
+        Subscription attachSub = observable.compose(RxLifecycle.bindView(lifecycle)).subscribe();
+        assertFalse(attachSub.isUnsubscribed());
+        lifecycle.onNext(new Object());
+        assertTrue(attachSub.isUnsubscribed());
+    }
+
+    @Test
+    public void testBindViewLifecycleOtherObject() {
+        // Ensures it works with other types as well, and not just "Object"
+        BehaviorSubject<String> lifecycle = BehaviorSubject.create();
+        Subscription attachSub = observable.compose(RxLifecycle.bindView(lifecycle)).subscribe();
+        assertFalse(attachSub.isUnsubscribed());
+        lifecycle.onNext("");
+        assertTrue(attachSub.isUnsubscribed());
+    }
+
+    @Test
+    public void testBindView() {
+        Activity activity = Robolectric.buildActivity(Activity.class).create().get();
+        View view = new View(activity);
+        CopyOnWriteArrayList<View.OnAttachStateChangeListener> listeners = TestUtil.getAttachStateChangeListeners(view);
+
+        // Do the attach notification
+        if (listeners != null) {
+            for (View.OnAttachStateChangeListener listener : listeners) {
+                listener.onViewAttachedToWindow(view);
+            }
+        }
+
+        // Subscribe
+        Subscription viewAttachSub = observable.compose(RxLifecycle.bindView(view)).subscribe();
+        assertFalse(viewAttachSub.isUnsubscribed());
+        listeners = TestUtil.getAttachStateChangeListeners(view);
+        assertNotNull(listeners);
+        assertFalse(listeners.isEmpty());
+
+        // Now detach
+        for (View.OnAttachStateChangeListener listener : listeners) {
+            listener.onViewDetachedFromWindow(view);
+        }
+        assertTrue(viewAttachSub.isUnsubscribed());
+    }
 }

rxlifecycle/src/test/java/com/trello/rxlifecycle/TestUtil.java

@@ -0,0 +1,37 @@
+/**
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.trello.rxlifecycle;
+
+import android.view.View;
+
+import org.robolectric.util.ReflectionHelpers;
+
+import java.util.concurrent.CopyOnWriteArrayList;
+
+public class TestUtil {
+
+    /**
+     * Manually retrieve the view's attach state change listeners of an event. Robolectric
+     * doesn't currently support manually firing these, and it would seem the events are not called
+     * in normal Robolectric usage either.
+     *
+     * @param view View with listeners to notify
+     */
+    static CopyOnWriteArrayList<View.OnAttachStateChangeListener> getAttachStateChangeListeners(View view) {
+        Object listenerInfo = ReflectionHelpers.callInstanceMethod(view, "getListenerInfo");
+        return ReflectionHelpers.getField(listenerInfo, "mOnAttachStateChangeListeners");
+    }
+
+}