Add unit test for sub/unsub/sub bug.

Author: Treora

rxjava-core/src/main/java/rx/operators/OperationGroupBy.java

@@ -16,6 +16,7 @@
 package rx.operators;
 
 import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
 
 import java.util.Arrays;
 import java.util.Collection;
@@ -29,6 +30,7 @@
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.junit.Test;
+import org.mockito.InOrder;
 
 import rx.Observable;
 import rx.Observer;
@@ -556,6 +558,78 @@ public String toString() {
             }
         }
 
+        /*
+         * Test subscribing to a group, unsubscribing from it again, and subscribing to a next group
+         */
+        @Test
+        public void testSubscribeAndImmediatelyUnsubscribeFirstGroup() {
+            CounterSource source = new CounterSource();
+            @SuppressWarnings("unchecked")
+            final Observer<Integer> observer = mock(Observer.class);
+
+            Func1<Integer, Integer> modulo2 = new Func1<Integer, Integer>() {
+                @Override
+                public Integer call(Integer x) {
+                    return x%2;
+                }
+            };
+
+            Subscription outerSubscription = source.groupBy(modulo2).subscribe(new Action1<GroupedObservable<Integer, Integer>>() {
+                @Override
+                public void call(GroupedObservable<Integer, Integer> group) {
+                    Subscription innerSubscription = group.subscribe(observer);
+                    if (group.getKey() == 0) {
+                        // We immediately unsubscribe again from the even numbers
+                        innerSubscription.unsubscribe();
+                        // We should still get the group of odd numbers
+                    }
+                }
+            });
+            try {
+                source.thread.join();
+            } catch (InterruptedException ex) {
+            }
+
+            InOrder o = inOrder(observer);
+            // With a different implementation that subscribes to the group concurrently, we might actually receive 0.
+            o.verify(observer, never()).onNext(0);
+            o.verify(observer).onNext(1);
+            o.verify(observer, never()).onNext(2);
+            o.verify(observer).onNext(3);
+            o.verify(observer, never()).onNext(4);
+            o.verify(observer).onNext(5);
+            o.verify(observer, never()).onNext(6);
+            o.verify(observer).onNext(7);
+            o.verify(observer, never()).onNext(8);
+            o.verify(observer).onNext(9);
+        }
+
+        private class CounterSource extends Observable<Integer> {
+            public Thread thread = null;
+            @Override
+            public Subscription subscribe(final Observer<Integer> observer) {
+                thread = new Thread(new Runnable() {
+                    @Override
+                    public void run() {
+                        int i = 0;
+                        while (i < 10) {
+                            observer.onNext(i++);
+                            if (Thread.interrupted()) {
+                                return;
+                            }
+                        }
+                    }
+                });
+                thread.start();
+                return new Subscription() {
+                    @Override
+                    public void unsubscribe() {
+                        thread.interrupt();
+                    }
+                };
+            }
+        }
+
     }
 
 }