Add unit tests for TabIndexExtensions (#5722)

* Add check to FindNextElement

* Add unit tests for TabIndexExtensions

diff --git a/Xamarin.Forms.Core.UnitTests/TabIndexTests.cs b/Xamarin.Forms.Core.UnitTests/TabIndexTests.cs
new file mode 100644 (file)
index 0000000..63f0163
--- /dev/null
+++ b/Xamarin.Forms.Core.UnitTests/TabIndexTests.cs
@@ -0,0 +1,229 @@
+using NUnit.Framework;
+using System.Linq;
+
+namespace Xamarin.Forms.Core.UnitTests
+{
+       [TestFixture]
+       public class TabIndexTests : BaseTestFixture
+       {
+
+               [Test]
+               public void GetTabIndexesOnParentPage_ImplicitZero()
+               {
+                       var target = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 1 },
+                                       new Label { TabIndex = 0 },
+                                       new Label { TabIndex = 3 },
+                                       new Label { TabIndex = 2 },
+                               }
+                       };
+
+                       var page = new ContentPage { Content = target };
+
+                       var tabIndexes = target.GetTabIndexesOnParentPage(out int _);
+
+                       //StackLayout is technically the first element with TabIndex 0.
+                       Assert.AreEqual(target, tabIndexes[0][0]);
+               }
+
+               [Test]
+               public void GetTabIndexesOnParentPage_ExplicitZero()
+               {
+                       Label target = new Label { TabIndex = 0 };
+                       var stackLayout = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 1 },
+                                       target,
+                                       new Label { TabIndex = 3 },
+                                       new Label { TabIndex = 2 },
+                               }
+                       };
+
+                       var page = new ContentPage { Content = stackLayout };
+
+                       var tabIndexes = stackLayout.GetTabIndexesOnParentPage(out int _);
+
+                       Assert.AreEqual(target, tabIndexes[0][1]);
+               }
+
+               [Test]
+               public void GetTabIndexesOnParentPage_NegativeTabIndex()
+               {
+                       Label target = new Label { TabIndex = -1 };
+                       var stackLayout = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 1 },
+                                       target,
+                                       new Label { TabIndex = 3 },
+                                       new Label { TabIndex = 2 },
+                               }
+                       };
+
+                       var page = new ContentPage { Content = stackLayout };
+
+                       var tabIndexes = stackLayout.GetTabIndexesOnParentPage(out int _);
+
+                       Assert.AreEqual(target, tabIndexes[-1][0]);
+               }
+
+               [Test]
+               public void FindNextElement_Forward_NextTabIndex()
+               {
+                       Label target = new Label { TabIndex = 1 };
+                       Label nextElement = new Label { TabIndex = 2 };
+                       var stackLayout = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 1 },
+                                       target,
+                                       new Label { TabIndex = 3 },
+                                       nextElement,
+                               }
+                       };
+
+                       var page = new ContentPage { Content = stackLayout };
+
+                       var tabIndexes = stackLayout.GetTabIndexesOnParentPage(out int maxAttempts);
+
+                       int _ = target.TabIndex;
+
+                       var found = target.FindNextElement(true, tabIndexes, ref _);
+
+                       Assert.AreEqual(nextElement, found);
+               }
+
+               [Test]
+               public void FindNextElement_Forward_DeclarationOrder()
+               {
+                       Label target = new Label { TabIndex = 1 };
+                       Label nextElement = new Label { TabIndex = 2 };
+                       var stackLayout = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 1 },
+                                       target,
+                                       nextElement,
+                                       new Label { TabIndex = 2 },
+                               }
+                       };
+
+                       var page = new ContentPage { Content = stackLayout };
+
+                       var tabIndexes = stackLayout.GetTabIndexesOnParentPage(out int maxAttempts);
+
+                       int _ = target.TabIndex;
+
+                       var found = target.FindNextElement(true, tabIndexes, ref _);
+
+                       Assert.AreEqual(nextElement, found);
+               }
+
+               [Test]
+               public void FindNextElement_Forward_TabIndex()
+               {
+                       Label target = new Label { TabIndex = 1 };
+                       Label nextElement = new Label { TabIndex = 2 };
+                       var stackLayout = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 1 },
+                                       target,
+                                       nextElement,
+                                       new Label { TabIndex = 2 },
+                               }
+                       };
+
+                       var page = new ContentPage { Content = stackLayout };
+
+                       var tabIndexes = stackLayout.GetTabIndexesOnParentPage(out int maxAttempts);
+
+                       int tabIndex = target.TabIndex;
+
+                       var found = target.FindNextElement(true, tabIndexes, ref tabIndex);
+
+                       Assert.AreEqual(2, tabIndex);
+               }
+
+               [Test]
+               public void FindNextElement_Backward_NextTabIndex()
+               {
+                       Label target = new Label { TabIndex = 2 };
+                       Label nextElement = new Label { TabIndex = 1 };
+                       var stackLayout = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 3 },
+                                       target,
+                                       new Label { TabIndex = 3 },
+                                       nextElement,
+                               }
+                       };
+
+                       var page = new ContentPage { Content = stackLayout };
+
+                       var tabIndexes = stackLayout.GetTabIndexesOnParentPage(out int maxAttempts);
+
+                       int _ = target.TabIndex;
+
+                       var found = target.FindNextElement(false, tabIndexes, ref _);
+
+                       Assert.AreEqual(nextElement, found);
+               }
+
+               [Test]
+               public void FindNextElement_Backward_DeclarationOrder()
+               {
+                       Label target = new Label { TabIndex = 2 };
+                       Label nextElement = new Label { TabIndex = 1 };
+                       var stackLayout = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 3 },
+                                       target,
+                                       nextElement,
+                                       new Label { TabIndex = 1 },
+                               }
+                       };
+
+                       var page = new ContentPage { Content = stackLayout };
+
+                       var tabIndexes = stackLayout.GetTabIndexesOnParentPage(out int maxAttempts);
+
+                       int _ = target.TabIndex;
+
+                       var found = target.FindNextElement(false, tabIndexes, ref _);
+
+                       Assert.AreEqual(nextElement, found);
+               }
+
+               [Test]
+               public void FindNextElement_Backward_TabIndex()
+               {
+                       Label target = new Label { TabIndex = 2 };
+                       Label nextElement = new Label { TabIndex = 1 };
+                       var stackLayout = new StackLayout
+                       {
+                               Children = {
+                                       new Label { TabIndex = 3 },
+                                       target,
+                                       nextElement,
+                                       new Label { TabIndex = 2 },
+                               }
+                       };
+
+                       var page = new ContentPage { Content = stackLayout };
+
+                       var tabIndexes = stackLayout.GetTabIndexesOnParentPage(out int maxAttempts);
+
+                       int tabIndex = target.TabIndex;
+
+                       var found = target.FindNextElement(false, tabIndexes, ref tabIndex);
+
+                       Assert.AreEqual(1, tabIndex);
+               }
+       }
+}
\ No newline at end of file

diff --git a/Xamarin.Forms.Core.UnitTests/Xamarin.Forms.Core.UnitTests.csproj b/Xamarin.Forms.Core.UnitTests/Xamarin.Forms.Core.UnitTests.csproj
index 39ddee3..33158f1 100644 (file)
--- a/Xamarin.Forms.Core.UnitTests/Xamarin.Forms.Core.UnitTests.csproj
+++ b/Xamarin.Forms.Core.UnitTests/Xamarin.Forms.Core.UnitTests.csproj
@@ -86,6 +86,7 @@
     <Compile Include="RegionTests.cs" />
     <Compile Include="ShellTests.cs" />
     <Compile Include="SpanTests.cs" />
+    <Compile Include="TabIndexTests.cs" />
     <Compile Include="TitleViewUnitTests.cs" />
     <Compile Include="TemplatedViewUnitTests.cs" />
     <Compile Include="TemplatedPageUnitTests.cs" />

diff --git a/Xamarin.Forms.Core/TabIndexExtensions.cs b/Xamarin.Forms.Core/TabIndexExtensions.cs
index ddd575b..4dc928e 100644 (file)
--- a/Xamarin.Forms.Core/TabIndexExtensions.cs
+++ b/Xamarin.Forms.Core/TabIndexExtensions.cs
@@ -32,7 +32,9 @@ namespace Xamarin.Forms
 
                public static VisualElement FindNextElement(this VisualElement element, bool forwardDirection, IDictionary<int, List<VisualElement>> tabIndexes, ref int tabIndex)
                {
-                       var tabGroup = tabIndexes[tabIndex];
+                       if (!tabIndexes.TryGetValue(tabIndex, out var tabGroup))
+                               return null;
+
                        if (!forwardDirection)
                        {
                                // search prev element in same TabIndex group