Empty doesn't raise events.

jamesmontemagno · Apr 26, 2019 · 3426744 · 3426744
1 parent 0fc604c
commit 3426744
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Showing 2 changed files with 60 additions and 16 deletions.
diff --git a/MvvmHelpers.UnitTests/ObservableRangeTests.cs b/MvvmHelpers.UnitTests/ObservableRangeTests.cs
@@ -14,17 +14,17 @@ public void AddRange()
         {
             ObservableRangeCollection<int> collection = new ObservableRangeCollection<int>();
             int[] toAdd = new[] { 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, 7, 9, 3, 2, 3 };
-            
+
             collection.CollectionChanged += (s, e) =>
             {
                 Assert.AreEqual(e.Action,
                                NotifyCollectionChangedAction.Add,
                                "AddRange didn't use Add like requested.");
 
                 Assert.IsNull(e.OldItems, "OldItems should be null.");
-                
-                Assert.AreEqual(toAdd.Length, 
-                                e.NewItems.Count, 
+
+                Assert.AreEqual(toAdd.Length,
+                                e.NewItems.Count,
                                 "Expected and actual OldItems don't match.");
 
                 for (int i = 0; i < toAdd.Length; i++)
@@ -36,6 +36,19 @@ public void AddRange()
             collection.AddRange(toAdd);
         }
 
+        [TestMethod]
+        public void AddRangeEmpty()
+        {
+            ObservableRangeCollection<int> collection = new ObservableRangeCollection<int>();
+            int[] toAdd = new int[0];
+
+            collection.CollectionChanged += (s, e) =>
+            {
+                Assert.Fail("The event is raised.");
+            };
+            collection.AddRange(toAdd);
+        }
+
         [TestMethod]
         public void ReplaceRange()
         {
@@ -89,6 +102,20 @@ public void RemoveRangeRemoveTestMethod()
             collection.RemoveRange(toRemove, NotifyCollectionChangedAction.Remove);
 
         }
+
+        [TestMethod]
+        public void RemoveRangeEmpty()
+        {
+            ObservableRangeCollection<int> collection = new ObservableRangeCollection<int>();
+            int[] toAdd = new[] { 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, 7, 9, 3, 2, 3 };
+            int[] toRemove = new int[0];
+            collection.AddRange(toAdd);
+            collection.CollectionChanged += (s, e) =>
+            {
+                Assert.Fail("The event is raised.");
+            };
+            collection.RemoveRange(toRemove, NotifyCollectionChangedAction.Remove);
+        }
     }
 }
 
diff --git a/MvvmHelpers/ObservableRangeCollection.cs b/MvvmHelpers/ObservableRangeCollection.cs
@@ -46,12 +46,19 @@ public void AddRange(IEnumerable<T> collection, NotifyCollectionChangedAction no
 
             if (notificationMode == NotifyCollectionChangedAction.Reset)
             {
+                bool raiseEvents = false;
                 foreach (var i in collection)
+                {
                     Items.Add(i);
+                    raiseEvents = true;
+                }
 
-                OnPropertyChanged(new PropertyChangedEventArgs("Count"));
-                OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
-                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+                if (raiseEvents)
+                {
+                    OnPropertyChanged(new PropertyChangedEventArgs("Count"));
+                    OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
+                    OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+                }
 
                 return;
             }
@@ -61,9 +68,12 @@ public void AddRange(IEnumerable<T> collection, NotifyCollectionChangedAction no
             foreach (var i in changedItems)
                 Items.Add(i);
 
-            OnPropertyChanged(new PropertyChangedEventArgs("Count"));
-            OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
-            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, changedItems, startIndex));
+            if (changedItems.Count > 0)
+            {
+                OnPropertyChanged(new PropertyChangedEventArgs("Count"));
+                OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
+                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, changedItems, startIndex));
+            }
         }
 
         /// <summary> 
@@ -80,15 +90,19 @@ public void RemoveRange(IEnumerable<T> collection, NotifyCollectionChangedAction
 
             if (notificationMode == NotifyCollectionChangedAction.Reset)
             {
-
+                bool raiseEvents = false;
                 foreach (var i in collection)
+                {
                     Items.Remove(i);
+                    raiseEvents = true;
+                }
 
-                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+                if (raiseEvents)
+                    OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
 
                 return;
             }
-            
+
             var changedItems = collection is List<T> ? (List<T>)collection : new List<T>(collection);
             for (int i = 0; i < changedItems.Count; i++)
             {
@@ -99,9 +113,12 @@ public void RemoveRange(IEnumerable<T> collection, NotifyCollectionChangedAction
                 }
             }
 
-            OnPropertyChanged(new PropertyChangedEventArgs("Count"));
-            OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
-            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, changedItems, -1));
+            if (changedItems.Count > 0)
+            {
+                OnPropertyChanged(new PropertyChangedEventArgs("Count"));
+                OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
+                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, changedItems, -1));
+            }
         }
 
         /// <summary>