Visual Studio Unit Testing Extensions

using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;

namespace CodeProject.VisualStudio.QualityTools.UnitTestFramework
{
    public sealed class CollectionChangedWatcher
    {
        private INotifyCollectionChanged watchedObject;
        private List<NotifyCollectionChangedEventArgs> events = new List<NotifyCollectionChangedEventArgs>();

        public CollectionChangedWatcher(INotifyCollectionChanged watchedObject)
        {
            this.watchedObject = watchedObject;
            this.watchedObject.CollectionChanged += watchedObject_CollectionChanged;
        }

        public void Reset()
        {
            events.Clear();
        }

        public IEnumerator<NotifyCollectionChangedEventArgs> Find(NotifyCollectionChangedAction action)
        {
            foreach (NotifyCollectionChangedEventArgs e in events)
            {
                if (e.Action.Equals(action))
                {
                    yield return e;
                }
            }
        }

        public IEnumerator<NotifyCollectionChangedEventArgs> Find(NotifyCollectionChangedAction action, ICollection items)
        {
            foreach (NotifyCollectionChangedEventArgs e in events)
            {
                if (e.Action.Equals(action))
                {
                    ICollection eventItems = null;
                    switch (action)
                    {
                        case NotifyCollectionChangedAction.Add:
                            eventItems = e.NewItems;
                            break;

                        case NotifyCollectionChangedAction.Remove:
                            eventItems = e.OldItems;
                            break;

                        default:
                            continue;
                    }
                    if (items.Count != eventItems.Count)
                        continue;

                    int actualOccurrences;
                    int expectedOccurrences;
                    object mismatchedObject;
                    if (Specify.FindMismatchedElement(eventItems, items, out actualOccurrences,
                        out expectedOccurrences, out mismatchedObject))
                    {
                        continue;
                    }

                    yield return e;
                }
            }
        }

        public IEnumerator<NotifyCollectionChangedEventArgs> Find(
            NotifyCollectionChangedAction action, ICollection newItems, ICollection oldItems)
        {
            foreach (NotifyCollectionChangedEventArgs e in events)
            {
                if (e.Action.Equals(action))
                {
                    if (newItems.Count != e.NewItems.Count || oldItems.Count != e.OldItems.Count)
                        continue;

                    int actualOccurrences;
                    int expectedOccurrences;
                    object mismatchedObject;

                    if (Specify.FindMismatchedElement(e.NewItems, newItems, out actualOccurrences,
                        out expectedOccurrences, out mismatchedObject))
                    {
                        continue;
                    }

                    if (Specify.FindMismatchedElement(e.OldItems, oldItems, out actualOccurrences,
                        out expectedOccurrences, out mismatchedObject))
                    {
                        continue;
                    }

                    yield return e;
                }
            }
        }

        private void watchedObject_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            events.Add(e);
        }
    }
}