2.x: Improve coverage and fix small mistakes/untaken paths in operators (#5883)

Author: akarnokd

src/main/java/io/reactivex/Maybe.java

@@ -888,7 +888,7 @@ public static <T> Flowable<T> merge(Publisher<? extends MaybeSource<? extends T>
     public static <T> Flowable<T> merge(Publisher<? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
         ObjectHelper.requireNonNull(sources, "source is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
-        return RxJavaPlugins.onAssembly(new FlowableFlatMapPublisher(sources, MaybeToPublisher.instance(), false, maxConcurrency, Flowable.bufferSize()));
+        return RxJavaPlugins.onAssembly(new FlowableFlatMapPublisher(sources, MaybeToPublisher.instance(), false, maxConcurrency, 1));
     }
 
     /**
@@ -1222,12 +1222,11 @@ public static <T> Flowable<T> mergeDelayError(Iterable<? extends MaybeSource<? e
      *         {@code source} Publisher
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
      */
-    @SuppressWarnings({ "unchecked", "rawtypes" })
     @BackpressureSupport(BackpressureKind.FULL)
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Flowable<T> mergeDelayError(Publisher<? extends MaybeSource<? extends T>> sources) {
-        return Flowable.fromPublisher(sources).flatMap((Function)MaybeToPublisher.instance(), true);
+        return mergeDelayError(sources, Integer.MAX_VALUE);
     }
 
 
@@ -1267,7 +1266,9 @@ public static <T> Flowable<T> mergeDelayError(Publisher<? extends MaybeSource<?
     @SchedulerSupport(SchedulerSupport.NONE)
     @Experimental
     public static <T> Flowable<T> mergeDelayError(Publisher<? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
-        return Flowable.fromPublisher(sources).flatMap((Function)MaybeToPublisher.instance(), true, maxConcurrency);
+        ObjectHelper.requireNonNull(sources, "source is null");
+        ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
+        return RxJavaPlugins.onAssembly(new FlowableFlatMapPublisher(sources, MaybeToPublisher.instance(), true, maxConcurrency, 1));
     }
 
     /**

src/main/java/io/reactivex/internal/operators/flowable/FlowableFlatMap.java

@@ -185,10 +185,10 @@ boolean addInner(InnerSubscriber<T, U> inner) {
         void removeInner(InnerSubscriber<T, U> inner) {
             for (;;) {
                 InnerSubscriber<?, ?>[] a = subscribers.get();
-                if (a == CANCELLED || a == EMPTY) {
+                int n = a.length;
+                if (n == 0) {
                     return;
                 }
-                int n = a.length;
                 int j = -1;
                 for (int i = 0; i < n; i++) {
                     if (a[i] == inner) {