Add unit tests for UITreeBuilder

Blazor.sln

@@ -52,7 +52,9 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.Blazor.Build", "s
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.Blazor.Browser.JS", "src\Microsoft.Blazor.Browser.JS\Microsoft.Blazor.Browser.JS.csproj", "{8A19B1CE-9B62-4440-93B3-152DDBB39D0A}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.Blazor.Browser", "src\Microsoft.Blazor.Browser\Microsoft.Blazor.Browser.csproj", "{4874AFF4-335D-4037-8858-BBBB987C124B}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.Blazor.Browser", "src\Microsoft.Blazor.Browser\Microsoft.Blazor.Browser.csproj", "{4874AFF4-335D-4037-8858-BBBB987C124B}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.Blazor.Test", "test\Microsoft.Blazor.Test\Microsoft.Blazor.Test.csproj", "{8FD8636E-AFA5-434D-8857-06D02686741A}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -132,6 +134,10 @@ Global
 		{4874AFF4-335D-4037-8858-BBBB987C124B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{4874AFF4-335D-4037-8858-BBBB987C124B}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{4874AFF4-335D-4037-8858-BBBB987C124B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{8FD8636E-AFA5-434D-8857-06D02686741A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8FD8636E-AFA5-434D-8857-06D02686741A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8FD8636E-AFA5-434D-8857-06D02686741A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{8FD8636E-AFA5-434D-8857-06D02686741A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -158,6 +164,7 @@ Global
 		{8B3D0F1C-0E38-4E6D-BFF1-C4FDA0CD9815} = {B867E038-B3CE-43E3-9292-61568C46CDEB}
 		{8A19B1CE-9B62-4440-93B3-152DDBB39D0A} = {B867E038-B3CE-43E3-9292-61568C46CDEB}
 		{4874AFF4-335D-4037-8858-BBBB987C124B} = {B867E038-B3CE-43E3-9292-61568C46CDEB}
+		{8FD8636E-AFA5-434D-8857-06D02686741A} = {ADA3AE29-F6DE-49F6-8C7C-B321508CAE8E}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {504DA352-6788-4DC0-8705-82167E72A4D3}

test/Microsoft.Blazor.Test/Microsoft.Blazor.Test.csproj

@@ -0,0 +1,20 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.0</TargetFramework>
+
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0" />
+    <PackageReference Include="xunit" Version="2.3.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
+    <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\Microsoft.Blazor\Microsoft.Blazor.csproj" />
+  </ItemGroup>
+
+</Project>

test/Microsoft.Blazor.Test/UITreeBuilderTest.cs

@@ -0,0 +1,164 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.Blazor.UITree;
+using System.Linq;
+using Xunit;
+
+namespace Microsoft.Blazor.Test
+{
+    public class UITreeBuilderTest
+    {
+        [Fact]
+        public void StartsEmpty()
+        {
+            // Arrange
+            var builder = new UITreeBuilder();
+
+            // Assert
+            var nodes = builder.GetNodes();
+            Assert.NotNull(nodes.Array);
+            Assert.Equal(0, nodes.Offset);
+            Assert.Empty(nodes);
+        }
+
+        [Fact]
+        public void CanAddText()
+        {
+            // Arrange
+            var builder = new UITreeBuilder();
+
+            // Act
+            builder.AddText("First item");
+            builder.AddText("Second item");
+
+            // Assert
+            var nodes = builder.GetNodes();
+            Assert.Equal(0, nodes.Offset);
+            Assert.Collection(nodes,
+                node => AssertText(node, "First item"),
+                node => AssertText(node, "Second item"));
+        }
+
+        [Fact]
+        public void UnclosedElementsHaveNoEndDescendantIndex()
+        {
+            // Arrange
+            var builder = new UITreeBuilder();
+
+            // Act
+            builder.OpenElement("my element");
+
+            // Assert
+            var node = builder.GetNodes().Single();
+            AssertElement(node, "my element", 0);
+        }
+
+        [Fact]
+        public void ClosedEmptyElementsHaveSelfAsEndDescendantIndex()
+        {
+            // Arrange
+            var builder = new UITreeBuilder();
+
+            // Act
+            builder.AddText("some node so that the element isn't at position zero");
+            builder.OpenElement("my element");
+            builder.CloseElement();
+
+            // Assert
+            var nodes = builder.GetNodes();
+            Assert.Equal(2, nodes.Count);
+            AssertElement(nodes[1], "my element", 1);
+        }
+
+        [Fact]
+        public void ClosedElementsHaveCorrectEndDescendantIndex()
+        {
+            // Arrange
+            var builder = new UITreeBuilder();
+
+            // Act
+            builder.OpenElement("my element");
+            builder.AddText("child 1");
+            builder.AddText("child 2");
+            builder.CloseElement();
+            builder.AddText("unrelated item");
+
+            // Assert
+            var nodes = builder.GetNodes();
+            Assert.Equal(4, nodes.Count);
+            AssertElement(nodes[0], "my element", 2);
+        }
+
+        [Fact]
+        public void CanNestElements()
+        {
+            // Arrange
+            var builder = new UITreeBuilder();
+
+            // Act
+            builder.AddText("standalone text 1");   //  0: standalone text 1
+            builder.OpenElement("root");            //  1: <root>
+            builder.AddText("root text 1");         //  2:     root text 1
+            builder.AddText("root text 2");         //  3:     root text 2
+            builder.OpenElement("child");           //  4:     <child>
+            builder.AddText("child text");          //  5:         child text
+            builder.OpenElement("grandchild");      //  6:         <grandchild>
+            builder.AddText("grandchild text 1");   //  7:             grandchild text 1
+            builder.AddText("grandchild text 2");   //  8:             grandchild text 2
+            builder.CloseElement();                 //             </grandchild>
+            builder.CloseElement();                 //         </child>
+            builder.AddText("root text 3");         //  9:     root text 3
+            builder.OpenElement("child 2");         // 10:     <child 2>
+            builder.CloseElement();                 //         </child 2>
+            builder.CloseElement();                 //      </root>
+            builder.AddText("standalone text 2");   // 11:  standalone text 2
+
+            // Assert
+            Assert.Collection(builder.GetNodes(),
+                node => AssertText(node, "standalone text 1"),
+                node => AssertElement(node, "root", 10),
+                node => AssertText(node, "root text 1"),
+                node => AssertText(node, "root text 2"),
+                node => AssertElement(node, "child", 8),
+                node => AssertText(node, "child text"),
+                node => AssertElement(node, "grandchild", 8),
+                node => AssertText(node, "grandchild text 1"),
+                node => AssertText(node, "grandchild text 2"),
+                node => AssertText(node, "root text 3"),
+                node => AssertElement(node, "child 2", 10),
+                node => AssertText(node, "standalone text 2"));
+        }
+
+        [Fact]
+        public void CanClear()
+        {
+            // Arrange
+            var builder = new UITreeBuilder();
+
+            // Act
+            builder.AddText("some text");
+            builder.OpenElement("elem");
+            builder.AddText("more text");
+            builder.CloseElement();
+            builder.Clear();
+
+            // Assert
+            Assert.Empty(builder.GetNodes());
+        }
+
+        void AssertText(UITreeNode node, string textContent)
+        {
+            Assert.Equal(UITreeNodeType.Text, node.NodeType);
+            Assert.Equal(textContent, node.TextContent);
+            Assert.Equal(0, node.ElementDescendantsEndIndex);
+        }
+
+        void AssertElement(UITreeNode node, string elementName, int descendantsEndIndex)
+        {
+            Assert.Equal(UITreeNodeType.Element, node.NodeType);
+            Assert.Equal(elementName, node.ElementName);
+            Assert.Equal(descendantsEndIndex, node.ElementDescendantsEndIndex);
+        }
+    }
+}