Add tests to validate TagHelperExecutionContexts Items bag.

- Added TagHelperScopeManager tests to ensure that the Items bag is correctly wrapped.
- Added test to TagHelperExecutionContext to make sure items bags are properly propogated.
- Updated existing unit tests to abide by the new constructor format of TagHelperScopeManager, TagHelperContext and TagHelperExecutionContext

#238

test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperContextTest.cs

@@ -0,0 +1,37 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
+{
+    public class TagHelperContextTest
+    {
+        [Fact]
+        public void Constructor_SetsProperties_AsExpected()
+        {
+            // Arrange
+            var expectedItems = new Dictionary<object, object>
+            {
+                { "test-entry", 1234 }
+            };
+
+            // Act
+            var context = new TagHelperContext(
+                allAttributes: new Dictionary<string, object>(),
+                items: expectedItems,
+                uniqueId: string.Empty,
+                getChildContentAsync: () => Task.FromResult(string.Empty));
+
+            // Assert
+            Assert.NotNull(context.Items);
+            Assert.Same(expectedItems, context.Items);
+            var item = Assert.Single(context.Items);
+            Assert.Equal("test-entry", (string)item.Key, StringComparer.Ordinal);
+            Assert.Equal(1234, item.Value);
+        }
+    }
+}

test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperExecutionContextTest.cs

@@ -25,6 +25,30 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             Assert.Equal(selfClosing, executionContext.SelfClosing);
         }
 
+        [Fact]
+        public void ParentItems_SetsItemsProperty()
+        {
+            // Arrange
+            var expectedItems = new Dictionary<object, object>
+            {
+                { "test-entry", 1234 }
+            };
+
+            // Act
+            var executionContext = new TagHelperExecutionContext(
+                "p",
+                selfClosing: false,
+                items: expectedItems,
+                uniqueId: string.Empty,
+                executeChildContentAsync: async () => await Task.FromResult(result: true),
+                startWritingScope: () => { },
+                endWritingScope: () => new StringWriter());
+
+            // Assert
+            Assert.NotNull(executionContext.Items);
+            Assert.Same(expectedItems, executionContext.Items);
+        }
+
         [Fact]
         public async Task GetChildContentAsync_CachesValue()
         {
@@ -34,6 +58,7 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             var executionContext = new TagHelperExecutionContext(
                 "p",
                 selfClosing: false,
+                items: null,
                 uniqueId: string.Empty,
                 executeChildContentAsync: () =>
                 {
@@ -67,6 +92,7 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             var executionContext = new TagHelperExecutionContext(
                 "p",
                 selfClosing: false,
+                items: null,
                 uniqueId: string.Empty,
                 executeChildContentAsync: () =>
                 {

test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperRunnerTest.cs

@@ -157,6 +157,23 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             Assert.Equal("True", output.Attributes["foo"]);
         }
 
+        [Fact]
+        public async Task RunAsync_ConfiguresTagHelperContextWithExecutionContextsItems()
+        {
+            // Arrange
+            var runner = new TagHelperRunner();
+            var executionContext = new TagHelperExecutionContext("p", selfClosing: false);
+            var tagHelper = new ContextInspectingTagHelper();
+            executionContext.Add(tagHelper);
+
+            // Act
+            await runner.RunAsync(executionContext);
+
+            // Assert
+            Assert.NotNull(tagHelper.ContextProcessedWith);
+            Assert.Same(tagHelper.ContextProcessedWith.Items, executionContext.Items);
+        }
+
         private class ExecutableTagHelper : TagHelper
         {
             public bool Processed { get; set; }
@@ -172,6 +189,16 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             }
         }
 
+        private class ContextInspectingTagHelper : TagHelper
+        {
+            public TagHelperContext ContextProcessedWith { get; set; }
+
+            public override void Process(TagHelperContext context, TagHelperOutput output)
+            {
+                ContextProcessedWith = context;
+            }
+        }
+
         private class TagHelperContextTouchingTagHelper : TagHelper
         {
             public override void Process(TagHelperContext context, TagHelperOutput output)

test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperScopeManagerTest.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
@@ -11,10 +12,118 @@ namespace Microsoft.AspNet.Razor.Runtime.Test.TagHelpers
 {
     public class TagHelperScopeManagerTest
     {
-        private static readonly Action DefaultStartWritingScope = () => { };
+        [Fact]
-        private static readonly Func<TextWriter> DefaultEndWritingScope = () => new StringWriter();
+        public void Begin_DoesNotRequireParentExecutionContext()
-        private static readonly Func<Task> DefaultExecuteChildContentAsync =
+        {
-            async () => await Task.FromResult(result: true);
+            // Arrange & Act
+            var scopeManager = new TagHelperScopeManager();
+
+            // Act
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
+            executionContext.Items["test-entry"] = 1234;
+
+            // Assert
+            var executionContextItem = Assert.Single(executionContext.Items);
+            Assert.Equal("test-entry", (string)executionContextItem.Key, StringComparer.Ordinal);
+            Assert.Equal(1234, executionContextItem.Value);
+        }
+
+        [Fact]
+        public void Begin_ReturnedExecutionContext_ItemsAreRetrievedFromParentExecutionContext()
+        {
+            // Arrange
+            var scopeManager = new TagHelperScopeManager();
+            var parentExecutionContext = BeginDefaultScope(scopeManager, tagName: "p");
+            parentExecutionContext.Items["test-entry"] = 1234;
+
+            // Act
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
+
+            // Assert
+            var executionContextItem = Assert.Single(executionContext.Items);
+            Assert.Equal("test-entry", (string)executionContextItem.Key, StringComparer.Ordinal);
+            Assert.Equal(1234, executionContextItem.Value);
+        }
+
+        [Fact]
+        public void Begin_DoesShallowCopyOfParentItems()
+        {
+            // Arrange
+            var scopeManager = new TagHelperScopeManager();
+            var parentComplexObject = new Dictionary<string, int>(StringComparer.Ordinal);
+            var parentExecutionContext = BeginDefaultScope(scopeManager, tagName: "p");
+            parentExecutionContext.Items["test-entry"] = parentComplexObject;
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
+
+            // Act
+            ((Dictionary<string, int>)executionContext.Items["test-entry"]).Add("from-child", 1234);
+
+            // Assert
+            var executionContextItem = Assert.Single(executionContext.Items);
+            Assert.Equal("test-entry", (string)executionContextItem.Key, StringComparer.Ordinal);
+            Assert.Same(parentComplexObject, executionContextItem.Value);
+            var parentEntry = Assert.Single(parentComplexObject);
+            Assert.Equal("from-child", parentEntry.Key, StringComparer.Ordinal);
+            Assert.Equal(1234, parentEntry.Value);
+        }
+
+        [Fact]
+        public void Begin_ReturnedExecutionContext_ItemsModificationDoesNotAffectParent()
+        {
+            // Arrange
+            var scopeManager = new TagHelperScopeManager();
+            var parentExecutionContext = BeginDefaultScope(scopeManager, tagName: "p");
+            parentExecutionContext.Items["test-entry"] = 1234;
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
+
+            // Act
+            executionContext.Items["test-entry"] = 2222;
+
+            // Assert
+            var executionContextItem = Assert.Single(executionContext.Items);
+            Assert.Equal("test-entry", (string)executionContextItem.Key, StringComparer.Ordinal);
+            Assert.Equal(2222, executionContextItem.Value);
+            var parentExecutionContextItem = Assert.Single(parentExecutionContext.Items);
+            Assert.Equal("test-entry", (string)parentExecutionContextItem.Key, StringComparer.Ordinal);
+            Assert.Equal(1234, parentExecutionContextItem.Value);
+        }
+
+        [Fact]
+        public void Begin_ReturnedExecutionContext_ItemsInsertionDoesNotAffectParent()
+        {
+            // Arrange
+            var scopeManager = new TagHelperScopeManager();
+            var parentExecutionContext = BeginDefaultScope(scopeManager, tagName: "p");
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
+
+            // Act
+            executionContext.Items["new-entry"] = 2222;
+
+            // Assert
+            var executionContextItem = Assert.Single(executionContext.Items);
+            Assert.Equal("new-entry", (string)executionContextItem.Key, StringComparer.Ordinal);
+            Assert.Equal(2222, executionContextItem.Value);
+            Assert.Empty(parentExecutionContext.Items);
+        }
+
+        [Fact]
+        public void Begin_ReturnedExecutionContext_ItemsRemovalDoesNotAffectParent()
+        {
+            // Arrange
+            var scopeManager = new TagHelperScopeManager();
+            var parentExecutionContext = BeginDefaultScope(scopeManager, tagName: "p");
+            parentExecutionContext.Items["test-entry"] = 1234;
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
+
+            // Act
+            executionContext.Items.Remove("test-entry");
+
+            // Assert
+            Assert.Empty(executionContext.Items);
+            var parentExecutionContextItem = Assert.Single(parentExecutionContext.Items);
+            Assert.Equal("test-entry", (string)parentExecutionContextItem.Key, StringComparer.Ordinal);
+            Assert.Equal(1234, parentExecutionContextItem.Value);
+        }
 
         [Fact]
         public void Begin_CreatesContextWithAppropriateTagName()
@@ -23,13 +132,7 @@ namespace Microsoft.AspNet.Razor.Runtime.Test.TagHelpers
             var scopeManager = new TagHelperScopeManager();
 
             // Act
-            var executionContext = scopeManager.Begin(
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
-                "p",
-                selfClosing: false,
-                uniqueId: string.Empty,
-                executeChildContentAsync: DefaultExecuteChildContentAsync,
-                startWritingScope: DefaultStartWritingScope,
-                endWritingScope: DefaultEndWritingScope);
 
             // Assert
             Assert.Equal("p", executionContext.TagName);
@@ -42,21 +145,8 @@ namespace Microsoft.AspNet.Razor.Runtime.Test.TagHelpers
             var scopeManager = new TagHelperScopeManager();
 
             // Act
-            var executionContext = scopeManager.Begin(
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
-                "p",
+            executionContext = BeginDefaultScope(scopeManager, tagName: "div");
-                selfClosing: false,
-                uniqueId: string.Empty,
-                executeChildContentAsync: DefaultExecuteChildContentAsync,
-                startWritingScope: DefaultStartWritingScope,
-                endWritingScope: DefaultEndWritingScope);
-
-            executionContext = scopeManager.Begin(
-               "div",
-               selfClosing: false,
-               uniqueId: string.Empty,
-               executeChildContentAsync: DefaultExecuteChildContentAsync,
-               startWritingScope: DefaultStartWritingScope,
-               endWritingScope: DefaultEndWritingScope);
 
             // Assert
             Assert.Equal("div", executionContext.TagName);
@@ -71,13 +161,7 @@ namespace Microsoft.AspNet.Razor.Runtime.Test.TagHelpers
             var scopeManager = new TagHelperScopeManager();
 
             // Act
-            var executionContext = scopeManager.Begin(
+            var executionContext = BeginDefaultScope(scopeManager, "p", selfClosing);
-                "p",
-                selfClosing: selfClosing,
-                uniqueId: string.Empty,
-                executeChildContentAsync: DefaultExecuteChildContentAsync,
-                startWritingScope: DefaultStartWritingScope,
-                endWritingScope: DefaultEndWritingScope);
 
             // Assert
             Assert.Equal(selfClosing, executionContext.SelfClosing);
@@ -90,22 +174,8 @@ namespace Microsoft.AspNet.Razor.Runtime.Test.TagHelpers
             var scopeManager = new TagHelperScopeManager();
 
             // Act
-            var executionContext = scopeManager.Begin(
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
-                "p",
+            executionContext = BeginDefaultScope(scopeManager, tagName: "div");
-                selfClosing: false,
-                uniqueId: string.Empty,
-                executeChildContentAsync: DefaultExecuteChildContentAsync,
-                startWritingScope: DefaultStartWritingScope,
-                endWritingScope: DefaultEndWritingScope);
-
-            executionContext = scopeManager.Begin(
-               "div",
-               selfClosing: false,
-               uniqueId: string.Empty,
-               executeChildContentAsync: DefaultExecuteChildContentAsync,
-               startWritingScope: DefaultStartWritingScope,
-               endWritingScope: DefaultEndWritingScope);
-
             executionContext = scopeManager.End();
 
             // Assert
@@ -119,22 +189,8 @@ namespace Microsoft.AspNet.Razor.Runtime.Test.TagHelpers
             var scopeManager = new TagHelperScopeManager();
 
             // Act
-            var executionContext = scopeManager.Begin(
+            var executionContext = BeginDefaultScope(scopeManager, tagName: "p");
-                "p",
+            executionContext = BeginDefaultScope(scopeManager, tagName: "div");
-                selfClosing: false,
-                uniqueId: string.Empty,
-                executeChildContentAsync: DefaultExecuteChildContentAsync,
-                startWritingScope: DefaultStartWritingScope,
-                endWritingScope: DefaultEndWritingScope);
-
-            executionContext = scopeManager.Begin(
-               "div",
-               selfClosing: false,
-               uniqueId: string.Empty,
-               executeChildContentAsync: DefaultExecuteChildContentAsync,
-               startWritingScope: DefaultStartWritingScope,
-               endWritingScope: DefaultEndWritingScope);
-
             executionContext = scopeManager.End();
             executionContext = scopeManager.End();
 
@@ -161,5 +217,19 @@ namespace Microsoft.AspNet.Razor.Runtime.Test.TagHelpers
 
             Assert.Equal(expectedError, ex.Message);
         }
+
+        private static TagHelperExecutionContext BeginDefaultScope(
+            TagHelperScopeManager scopeManager, 
+            string tagName,
+            bool selfClosing = false)
+        {
+            return scopeManager.Begin(
+                tagName,
+                selfClosing,
+                uniqueId: string.Empty,
+                executeChildContentAsync: async () => await Task.FromResult(result: true),
+                startWritingScope: () => { },
+                endWritingScope: () => new StringWriter());
+        }
     }
 }