Added ItemsPresenter tests.

Needed to allow it to not be part of ItemsControl template to allow
easier testing.

Perspex.Controls/Generators/ItemContainerGenerator.cs

@@ -20,7 +20,7 @@ namespace Perspex.Controls.Generators
 
         private ItemContainerGeneratorState state;
 
-        public ItemContainerGenerator(ItemsControl owner)
+        public ItemContainerGenerator(Control owner)
         {
             this.Owner = owner;
         }
@@ -48,7 +48,7 @@ namespace Perspex.Controls.Generators
             }
         }
 
-        protected ItemsControl Owner
+        protected Control Owner
         {
             get;
             private set;

Perspex.Controls/Presenters/ItemsPresenter.cs

@@ -29,6 +29,12 @@ namespace Perspex.Controls.Presenters
             this.GetObservableWithHistory(ItemsProperty).Subscribe(this.ItemsChanged);
         }
 
+        public ItemContainerGenerator ItemContainerGenerator
+        {
+            get;
+            private set;
+        }
+
         public IEnumerable Items
         {
             get { return this.GetValue(ItemsProperty); }
@@ -81,14 +87,13 @@ namespace Perspex.Controls.Presenters
 
         private IItemContainerGenerator GetGenerator()
         {
-            ItemsControl i = this.TemplatedParent as ItemsControl;
+            if (this.ItemContainerGenerator == null)
-
-            if (i == null)
             {
-                throw new InvalidOperationException("ItemsPresenter must be part of an ItemsControl template.");
+                ItemsControl i = this.TemplatedParent as ItemsControl;
+                this.ItemContainerGenerator = i?.ItemContainerGenerator ?? new ItemContainerGenerator(this);
             }
 
-            return i.ItemContainerGenerator;
+            return this.ItemContainerGenerator;
         }
 
         private void ItemsChanged(Tuple<IEnumerable, IEnumerable> value)

Tests/Perspex.Controls.UnitTests/Perspex.Controls.UnitTests.csproj

@@ -90,6 +90,7 @@
   <ItemGroup>
     <Compile Include="ContentPresenterTests.cs" />
     <Compile Include="DropDownTests.cs" />
+    <Compile Include="Presenters\ItemsPresenterTests.cs" />
     <Compile Include="ScrollContentPresenterTests.cs" />
     <Compile Include="ScrollViewerTests.cs" />
     <Compile Include="Primitives\SelectingItemsControlTests.cs" />

Tests/Perspex.Controls.UnitTests/Presenters/ItemsPresenterTests.cs

@@ -0,0 +1,77 @@
+// -----------------------------------------------------------------------
+// <copyright file="ItemsPresenterTests.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls.UnitTests.Presenters
+{
+    using Perspex.Controls.Presenters;
+    using Perspex.Input;
+    using Perspex.VisualTree;
+    using System.Linq;
+    using Xunit;
+
+    public class ItemsPresenterTests
+    {
+        [Fact]
+        public void Panel_Should_Be_Created_From_ItemsPanel_Template()
+        {
+            var panel = new Panel();
+            var target = new ItemsPresenter
+            {
+                ItemsPanel = new ItemsPanelTemplate(() => panel),
+            };
+
+            target.ApplyTemplate();
+
+            Assert.Equal(panel, target.Panel);
+        }
+
+        [Fact]
+        public void Panel_TemplatedParent_Should_Be_Set()
+        {
+            var target = new ItemsPresenter();
+
+            target.ApplyTemplate();
+
+            Assert.Equal(target, target.Panel.TemplatedParent);
+        }
+
+        [Fact]
+        public void Panel_TabNavigation_Should_Be_Set_To_Once()
+        {
+            var target = new ItemsPresenter();
+
+            target.ApplyTemplate();
+
+            Assert.Equal(KeyboardNavigationMode.Once, KeyboardNavigation.GetTabNavigation(target.Panel));
+        }
+
+        [Fact]
+        public void Panel_Should_Be_Visual_Child()
+        {
+            var target = new ItemsPresenter();
+
+            target.ApplyTemplate();
+
+            var child = target.GetVisualChildren().Single();
+
+            Assert.Equal(target.Panel, child);
+        }
+
+        [Fact]
+        public void Items_Should_Be_Created_On_ApplyTemplate()
+        {
+            var target = new ItemsPresenter
+            {
+                Items = new[] { "foo", "bar" },
+            };
+
+            target.ApplyTemplate();
+
+            Assert.Equal(2, target.Panel.GetVisualChildren().Count());
+        }
+    }
+}
+