1.x: add RxJavaHooks tests, fix small bugs (ReactiveX#4142)

* 1.x: add RxJavaHooks tests, fix small bugs

* Add onSchedule hook test

* Use static assert, update Conpletable param name

Author: akarnokd

src/main/java/rx/Completable.java

@@ -87,21 +87,21 @@ public interface CompletableTransformer extends Func1<Completable, Completable>
     }
 
     /** Single instance of a complete Completable. */
-    static final Completable COMPLETE = create(new CompletableOnSubscribe() {
+    static final Completable COMPLETE = new Completable(new CompletableOnSubscribe() {
         @Override
         public void call(CompletableSubscriber s) {
             s.onSubscribe(Subscriptions.unsubscribed());
             s.onCompleted();
         }
-    });
+    }, true); // hook is handled in complete()
 
     /** Single instance of a never Completable. */
-    static final Completable NEVER = create(new CompletableOnSubscribe() {
+    static final Completable NEVER = new Completable(new CompletableOnSubscribe() {
         @Override
         public void call(CompletableSubscriber s) {
             s.onSubscribe(Subscriptions.unsubscribed());
         }
-    });
+    }, true); // hook is handled in never()
 
     /**
      * Returns a Completable which terminates as soon as one of the source Completables
@@ -311,7 +311,11 @@ public void onSubscribe(Subscription d) {
      * @return a Completable instance that completes immediately 
      */
     public static Completable complete() {
-        return COMPLETE;
+        CompletableOnSubscribe cos = RxJavaHooks.onCreate(COMPLETE.onSubscribe);
+        if (cos == COMPLETE.onSubscribe) {
+            return COMPLETE;
+        }
+        return new Completable(cos, true);
     }
 
     /**
@@ -734,7 +738,11 @@ public static Completable mergeDelayError(Observable<? extends Completable> sour
      * @return the singleton instance that never calls onError or onComplete
      */
     public static Completable never() {
-        return NEVER;
+        CompletableOnSubscribe cos = RxJavaHooks.onCreate(NEVER.onSubscribe);
+        if (cos == NEVER.onSubscribe) {
+            return NEVER;
+        }
+        return new Completable(cos, true);
     }
 
     /**
@@ -975,7 +983,18 @@ public void call() {
     protected Completable(CompletableOnSubscribe onSubscribe) {
         this.onSubscribe = RxJavaHooks.onCreate(onSubscribe);
     }
-    
+
+    /**
+     * Constructs a Completable instance with the given onSubscribe callback without calling the onCreate
+     * hook.
+     * @param onSubscribe the callback that will receive CompletableSubscribers when they subscribe,
+     * not null (not verified)
+     * @param useHook if false, RxJavaHooks.onCreate won't be called
+     */
+    private Completable(CompletableOnSubscribe onSubscribe, boolean useHook) {
+        this.onSubscribe = useHook ? RxJavaHooks.onCreate(onSubscribe) : onSubscribe;
+    }
+
     /**
      * Returns a Completable that emits the a terminated event of either this Completable
      * or the other Completable whichever fires first.

src/main/java/rx/plugins/RxJavaHooks.java

@@ -171,6 +171,10 @@ public static void reset() {
             return;
         }
         init();
+        
+        onComputationScheduler = null;
+        onIOScheduler = null;
+        onNewThreadScheduler = null;
     }
 
     /**
@@ -224,7 +228,7 @@ public static void onError(Throwable ex) {
         Action1<Throwable> f = onError;
         if (f != null) {
             try {
-            f.call(ex);
+                f.call(ex);
                 return;
             } catch (Throwable pluginException) {
                 /*

src/main/java/rx/schedulers/Schedulers.java

@@ -137,7 +137,7 @@ public static Scheduler computation() {
      * @return a {@link Scheduler} meant for IO-bound work
      */
     public static Scheduler io() {
-        return RxJavaHooks.onComputationScheduler(getInstance().ioScheduler);
+        return RxJavaHooks.onIOScheduler(getInstance().ioScheduler);
     }
 
     /**