2.x: improve BaseTestConsumer with awaitCount & timeout (#5155)

* 2.x: improve BaseTestConsumer with awaitCount & timeout

* Improve diff coverage

Author: akarnokd

src/main/java/io/reactivex/internal/util/VolatileSizeArrayList.java

@@ -0,0 +1,187 @@
+/**
+ * Copyright (c) 2016-present, RxJava Contributors.
+ *
+ * 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 io.reactivex.internal.util;
+
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Tracks the current underlying array size in a volatile field.
+ *
+ * @param <T> the element type
+ * @since 2.0.7
+ */
+public final class VolatileSizeArrayList<T> extends AtomicInteger implements List<T> {
+
+    private static final long serialVersionUID = 3972397474470203923L;
+
+    final ArrayList<T> list;
+
+    public VolatileSizeArrayList() {
+        list = new ArrayList<T>();
+    }
+
+    public VolatileSizeArrayList(int initialCapacity) {
+        list = new ArrayList<T>(initialCapacity);
+    }
+
+    @Override
+    public int size() {
+        return get();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return get() == 0;
+    }
+
+    @Override
+    public boolean contains(Object o) {
+        return list.contains(o);
+    }
+
+    @Override
+    public Iterator<T> iterator() {
+        return list.iterator();
+    }
+
+    @Override
+    public Object[] toArray() {
+        return list.toArray();
+    }
+
+    @Override
+    public <E> E[] toArray(E[] a) {
+        return list.toArray(a);
+    }
+
+    @Override
+    public boolean add(T e) {
+        boolean b = list.add(e);
+        lazySet(list.size());
+        return b;
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        boolean b = list.remove(o);
+        lazySet(list.size());
+        return b;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> c) {
+        return list.containsAll(c);
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends T> c) {
+        boolean b = list.addAll(c);
+        lazySet(list.size());
+        return b;
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends T> c) {
+        boolean b = list.addAll(index, c);
+        lazySet(list.size());
+        return b;
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> c) {
+        boolean b = list.removeAll(c);
+        lazySet(list.size());
+        return b;
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> c) {
+        boolean b = list.retainAll(c);
+        lazySet(list.size());
+        return b;
+    }
+
+    @Override
+    public void clear() {
+        list.clear();
+        lazySet(0);
+    }
+
+    @Override
+    public T get(int index) {
+        return list.get(index);
+    }
+
+    @Override
+    public T set(int index, T element) {
+        return list.set(index, element);
+    }
+
+    @Override
+    public void add(int index, T element) {
+        list.add(index, element);
+        lazySet(list.size());
+    }
+
+    @Override
+    public T remove(int index) {
+        T v = list.remove(index);
+        lazySet(list.size());
+        return v;
+    }
+
+    @Override
+    public int indexOf(Object o) {
+        return list.indexOf(o);
+    }
+
+    @Override
+    public int lastIndexOf(Object o) {
+        return list.lastIndexOf(o);
+    }
+
+    @Override
+    public ListIterator<T> listIterator() {
+        return list.listIterator();
+    }
+
+    @Override
+    public ListIterator<T> listIterator(int index) {
+        return list.listIterator(index);
+    }
+
+    @Override
+    public List<T> subList(int fromIndex, int toIndex) {
+        return list.subList(fromIndex, toIndex);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj instanceof VolatileSizeArrayList) {
+            return list.equals(((VolatileSizeArrayList<?>)obj).list);
+        }
+        return list.equals(obj);
+    }
+
+    @Override
+    public int hashCode() {
+        return list.hashCode();
+    }
+
+    @Override
+    public String toString() {
+        return list.toString();
+    }
+}