From 58c479ae1071a77e0b31671dfcc08b7a15b56dfb Mon Sep 17 00:00:00 2001
From: "d.dovgopolyi" <d.dovgopolyi@fxpro.com>
Date: Fri, 14 Jun 2019 10:28:51 +0300
Subject: [PATCH] Fix And operator

---
 DynamicData.Tests/Cache/AndFixture.cs  | 13 +++++++++++++
 DynamicData.Tests/List/AndFixture.cs   | 11 +++++++++++
 DynamicData/Cache/Internal/Combiner.cs | 13 +++++++------
 DynamicData/List/Internal/Combiner.cs  | 16 +++++++++-------
 4 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/DynamicData.Tests/Cache/AndFixture.cs b/DynamicData.Tests/Cache/AndFixture.cs
index 3eec16182..d9f2b9100 100644
--- a/DynamicData.Tests/Cache/AndFixture.cs
+++ b/DynamicData.Tests/Cache/AndFixture.cs
@@ -95,5 +95,18 @@ public void UpdatingOneProducesOnlyOneUpdate()
             _results.Data.Count.Should().Be(1, "Cache should have no items");
             _results.Data.Items.First().Should().Be(personUpdated, "Should be updated person");
         }
+
+        [Fact]
+        public void StartingWithNonEmptySourceProducesNoResult()
+        {
+            var person = new Person("Adult", 50);
+            _source1.AddOrUpdate(person);
+
+            using (var result = CreateObservable().AsAggregator())
+            {
+                _results.Messages.Count.Should().Be(0, "Should have no updates");
+                result.Data.Count.Should().Be(0, "Cache should have no items");
+            }
+        }
     }
 }
diff --git a/DynamicData.Tests/List/AndFixture.cs b/DynamicData.Tests/List/AndFixture.cs
index d21e935ed..c5b309c37 100644
--- a/DynamicData.Tests/List/AndFixture.cs
+++ b/DynamicData.Tests/List/AndFixture.cs
@@ -90,5 +90,16 @@ public void ClearOneClearsResult()
             _source1.Clear();
             _results.Data.Count.Should().Be(0);
         }
+
+        [Fact]
+        public void StartingWithNonEmptySourceProducesNoResult()
+        {
+            _source1.Add(1);
+
+            using (var result = CreateObservable().AsAggregator())
+            {
+                result.Data.Count.Should().Be(0);
+            }
+        }
     }
 }
diff --git a/DynamicData/Cache/Internal/Combiner.cs b/DynamicData/Cache/Internal/Combiner.cs
index e5d85e6da..cce1e871e 100644
--- a/DynamicData/Cache/Internal/Combiner.cs
+++ b/DynamicData/Cache/Internal/Combiner.cs
@@ -30,15 +30,16 @@ public IDisposable Subscribe(IObservable<IChangeSet<TObject, TKey>>[] source)
             var disposable = new CompositeDisposable();
             lock (_locker)
             {
-                foreach (var item in source)
-                {
-                    var cache = new Cache<TObject, TKey>();
-                    _sourceCaches.Add(cache);
+                var caches = Enumerable.Range(0, source.Length).Select(_ => new Cache<TObject, TKey>());
+                _sourceCaches.AddRange(caches);
 
-                    var subsription = item.Subscribe(updates => Update(cache, updates));
-                    disposable.Add(subsription);
+                foreach (var pair in source.Zip(_sourceCaches, (item, cache) => new { Item = item, Cache = cache }))
+                {
+                    var subscription = pair.Item.Subscribe(updates => Update(pair.Cache, updates));
+                    disposable.Add(subscription);
                 }
             }
+
             return disposable;
         }
 
diff --git a/DynamicData/List/Internal/Combiner.cs b/DynamicData/List/Internal/Combiner.cs
index 69bca0cf8..0cab4175a 100644
--- a/DynamicData/List/Internal/Combiner.cs
+++ b/DynamicData/List/Internal/Combiner.cs
@@ -25,19 +25,20 @@ public IObservable<IChangeSet<T>> Run()
             return Observable.Create<IChangeSet<T>>(observer =>
             {
                 var disposable = new CompositeDisposable();
-                var sourceLists = new List<ReferenceCountTracker<T>>();
+
                 var resultList = new ChangeAwareListWithRefCounts<T>();
 
                 lock (_locker)
                 {
-                    foreach (var item in _source)
-                    {
-                        var list = new ReferenceCountTracker<T>();
-                        sourceLists.Add(list);
+                    var sourceLists = Enumerable.Range(0, _source.Count)
+                        .Select(_ => new ReferenceCountTracker<T>())
+                        .ToList(); 
 
-                        disposable.Add(item.Synchronize(_locker).Subscribe(changes =>
+                    foreach (var pair in _source.Zip(sourceLists, (item, list) => new { Item = item, List = list }))
+                    {
+                        disposable.Add(pair.Item.Synchronize(_locker).Subscribe(changes =>
                         {
-                            CloneSourceList(list, changes);
+                            CloneSourceList(pair.List, changes);
 
                             var notifications = UpdateResultList(changes, sourceLists, resultList);
                             if (notifications.Count != 0)
@@ -45,6 +46,7 @@ public IObservable<IChangeSet<T>> Run()
                         }));
                     }
                 }
+
                 return disposable;
             });
         }