From 57058f19cda987c1ca199f3957f09bdd12930f00 Mon Sep 17 00:00:00 2001
From: wojciech krysiak <wojciech.krysiak@gmail.com>
Date: Sun, 23 Sep 2018 10:11:49 +0200
Subject: [PATCH] Fix SelectedItemsChanged event arguments in
 SelectingItemsControl

---
 .../Primitives/SelectingItemsControl.cs       |  4 +--
 .../SelectingItemsControlTests_Multiple.cs    | 29 +++++++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
index bb39b005cc7..d7db04f369e 100644
--- a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
+++ b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
@@ -871,8 +871,8 @@ private void SelectedItemsCollectionChanged(object sender, NotifyCollectionChang
                         RaisePropertyChanged(SelectedItemProperty, oldItem, item, BindingPriority.LocalValue);
                     }
 
-                    added = e.OldItems;
-                    removed = e.NewItems;
+                    added = e.NewItems;
+                    removed = e.OldItems;
                     break;
             }
 
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs
index 3c6b278e07c..9ef7d567c8c 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs
@@ -541,6 +541,35 @@ public void Assigning_SelectedItems_Should_Raise_SelectionChanged()
             Assert.True(called);
         }
 
+        [Fact]
+        public void Replacing_SelectedItems_Should_Raise_SelectionChanged_With_CorrectItems()
+        {
+            var items = new[] { "foo", "bar", "baz" };
+
+            var target = new TestSelector
+            {
+                Items = items,
+                Template = Template(),
+                SelectedItem = "bar",
+            };
+
+            var called = false;
+
+            target.SelectionChanged += (s, e) =>
+            {
+                Assert.Equal(new[] { "foo",}, e.AddedItems.Cast<object>());
+                Assert.Equal(new[] { "bar" }, e.RemovedItems.Cast<object>());
+                called = true;
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+            target.SelectedItems[0] = "foo";
+
+            Assert.True(called);
+        }
+
+
         private FuncControlTemplate Template()
         {
             return new FuncControlTemplate<SelectingItemsControl>(control =>