diff --git a/src/Microsoft.AspNetCore.Mvc.Core/Properties/AssemblyInfo.cs b/src/Microsoft.AspNetCore.Mvc.Core/Properties/AssemblyInfo.cs
index f97bba2f7f..4adf6b6cd7 100644
--- a/src/Microsoft.AspNetCore.Mvc.Core/Properties/AssemblyInfo.cs
+++ b/src/Microsoft.AspNetCore.Mvc.Core/Properties/AssemblyInfo.cs
@@ -7,7 +7,6 @@ using System.Runtime.CompilerServices;
 
 [assembly: InternalsVisibleTo("Microsoft.AspNetCore.Mvc.Core.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("Microsoft.AspNetCore.Mvc.Razor.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
-[assembly: InternalsVisibleTo("Microsoft.AspNetCore.Mvc.TagHelpers.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7")]
 [assembly: AssemblyMetadata("Serviceable", "True")]
 [assembly: NeutralResourcesLanguage("en-us")]
diff --git a/src/Microsoft.AspNetCore.Mvc.ViewFeatures/Properties/AssemblyInfo.cs b/src/Microsoft.AspNetCore.Mvc.ViewFeatures/Properties/AssemblyInfo.cs
index e2811d2627..cb2cfb0eeb 100644
--- a/src/Microsoft.AspNetCore.Mvc.ViewFeatures/Properties/AssemblyInfo.cs
+++ b/src/Microsoft.AspNetCore.Mvc.ViewFeatures/Properties/AssemblyInfo.cs
@@ -7,7 +7,6 @@ using System.Runtime.CompilerServices;
 
 [assembly: InternalsVisibleTo("Microsoft.AspNetCore.Mvc.ViewFeatures.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("Microsoft.AspNetCore.Mvc.Razor.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
-[assembly: InternalsVisibleTo("Microsoft.AspNetCore.Mvc.TagHelpers.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("Microsoft.AspNetCore.Mvc.Formatters.Xml.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7")]
 [assembly: AssemblyMetadata("Serviceable", "True")]
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagHelperTest.cs
index 9f1ba25f35..db85bc3d23 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagHelperTest.cs
@@ -652,7 +652,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             var actionContext = new ActionContext(new DefaultHttpContext(), new RouteData(), new ActionDescriptor());
             return new ViewContext(actionContext,
                                    Mock.Of<IView>(),
-                                   new ViewDataDictionary(new EmptyModelMetadataProvider()),
+                                   new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary()),
                                    Mock.Of<ITempDataDictionary>(),
                                    TextWriter.Null,
                                    new HtmlHelperOptions());
@@ -683,5 +683,5 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
         }
-    }    
+    }
 }
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagKeyTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagKeyTest.cs
index a4285725c2..debed3c36f 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagKeyTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagKeyTest.cs
@@ -6,7 +6,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Security.Claims;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Internal;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
 using Microsoft.AspNetCore.Mvc.Rendering;
@@ -370,13 +369,13 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             // Assert
             Assert.Equal(expected, key);
         }
-        
+
         private static ViewContext GetViewContext()
         {
             var actionContext = new ActionContext(new DefaultHttpContext(), new RouteData(), new ActionDescriptor());
             return new ViewContext(actionContext,
                                    Mock.Of<IView>(),
-                                   new ViewDataDictionary(new EmptyModelMetadataProvider()),
+                                   new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary()),
                                    Mock.Of<ITempDataDictionary>(),
                                    TextWriter.Null,
                                    new HtmlHelperOptions());
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CaseSensitiveTagHelperAttributeComparer.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CaseSensitiveTagHelperAttributeComparer.cs
deleted file mode 100644
index c5c4a22cfb..0000000000
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CaseSensitiveTagHelperAttributeComparer.cs
+++ /dev/null
@@ -1,64 +0,0 @@
-// 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 System;
-using System.Collections.Generic;
-using System.IO;
-using Microsoft.AspNetCore.Html;
-using Microsoft.AspNetCore.Razor.TagHelpers;
-
-namespace Microsoft.AspNetCore.Mvc.TagHelpers
-{
-    public class CaseSensitiveTagHelperAttributeComparer : IEqualityComparer<TagHelperAttribute>
-    {
-        public readonly static CaseSensitiveTagHelperAttributeComparer Default =
-            new CaseSensitiveTagHelperAttributeComparer();
-
-        private CaseSensitiveTagHelperAttributeComparer()
-        {
-        }
-
-        public bool Equals(TagHelperAttribute attributeX, TagHelperAttribute attributeY)
-        {
-            if (attributeX == attributeY)
-            {
-                return true;
-            }
-
-            // Normal comparer (TagHelperAttribute.Equals()) doesn't care about the Name case, in tests we do.
-            return attributeX != null &&
-                string.Equals(attributeX.Name, attributeY.Name, StringComparison.Ordinal) &&
-                attributeX.ValueStyle == attributeY.ValueStyle &&
-                (attributeX.ValueStyle == HtmlAttributeValueStyle.Minimized ||
-                 string.Equals(GetString(attributeX.Value), GetString(attributeY.Value)));
-        }
-
-        public int GetHashCode(TagHelperAttribute attribute)
-        {
-            // Manually combine hash codes here. We can't reference HashCodeCombiner because we have internals visible
-            // from Mvc.Core and Mvc.TagHelpers; both of which reference HashCodeCombiner.
-            var baseHashCode = 0x1505L;
-            var attributeHashCode = attribute.GetHashCode();
-            var combinedHash = ((baseHashCode << 5) + baseHashCode) ^ attributeHashCode;
-            var nameHashCode = StringComparer.Ordinal.GetHashCode(attribute.Name);
-            combinedHash = ((combinedHash << 5) + combinedHash) ^ nameHashCode;
-
-            return combinedHash.GetHashCode();
-        }
-
-        private string GetString(object value)
-        {
-            var htmlContent = value as IHtmlContent;
-            if (htmlContent != null)
-            {
-                using (var writer = new StringWriter())
-                {
-                    htmlContent.WriteTo(writer, NullHtmlEncoder.Default);
-                    return writer.ToString();
-                }
-            }
-
-            return value?.ToString() ?? string.Empty;
-        }
-    }
-}
\ No newline at end of file
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/DistributedCacheTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/DistributedCacheTagHelperTest.cs
index 57cec0b647..147c0574a1 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/DistributedCacheTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/DistributedCacheTagHelperTest.cs
@@ -719,7 +719,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             var actionContext = new ActionContext(new DefaultHttpContext(), new RouteData(), new ActionDescriptor());
             return new ViewContext(actionContext,
                 Mock.Of<IView>(),
-                new ViewDataDictionary(new EmptyModelMetadataProvider()),
+                new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary()),
                 Mock.Of<ITempDataDictionary>(),
                 TextWriter.Null,
                 new HtmlHelperOptions());
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/FormTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/FormTagHelperTest.cs
index 5879eca4c0..9b3405306d 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/FormTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/FormTagHelperTest.cs
@@ -707,7 +707,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             return new ViewContext(
                 actionContext,
                 Mock.Of<IView>(),
-                new ViewDataDictionary(new TestModelMetadataProvider()),
+                new ViewDataDictionary(new TestModelMetadataProvider(), new ModelStateDictionary()),
                 Mock.Of<ITempDataDictionary>(),
                 TextWriter.Null,
                 new HtmlHelperOptions());
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ImageTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ImageTagHelperTest.cs
index 0f53b39a1b..040df4b37d 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ImageTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ImageTagHelperTest.cs
@@ -268,7 +268,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             }
 
             var metadataProvider = new EmptyModelMetadataProvider();
-            var viewData = new ViewDataDictionary(metadataProvider);
+            var viewData = new ViewDataDictionary(metadataProvider, new ModelStateDictionary());
             var viewContext = new ViewContext(
                 actionContext,
                 Mock.Of<IView>(),
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/InputTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/InputTagHelperTest.cs
index e4a4831239..e7718c5214 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/InputTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/InputTagHelperTest.cs
@@ -13,6 +13,7 @@ using Microsoft.AspNetCore.Mvc.TestCommon;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
 using Microsoft.AspNetCore.Razor.TagHelpers;
+using Microsoft.AspNetCore.Razor.TagHelpers.Testing;
 using Moq;
 using Xunit;
 
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/LinkTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/LinkTagHelperTest.cs
index 5f047a3a1b..1260e57083 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/LinkTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/LinkTagHelperTest.cs
@@ -984,7 +984,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             }
 
             var metadataProvider = new EmptyModelMetadataProvider();
-            var viewData = new ViewDataDictionary(metadataProvider);
+            var viewData = new ViewDataDictionary(metadataProvider, new ModelStateDictionary());
             var viewContext = new ViewContext(
                 actionContext,
                 Mock.Of<IView>(),
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ScriptTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ScriptTagHelperTest.cs
index 74b862f24b..4a2e7f6241 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ScriptTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ScriptTagHelperTest.cs
@@ -922,7 +922,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             }
 
             var metadataProvider = new EmptyModelMetadataProvider();
-            var viewData = new ViewDataDictionary(metadataProvider);
+            var viewData = new ViewDataDictionary(metadataProvider, new ModelStateDictionary());
             var viewContext = new ViewContext(
                 actionContext,
                 Mock.Of<IView>(),
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/TagHelperOutputExtensionsTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/TagHelperOutputExtensionsTest.cs
index 0011cbcf0c..3e70b3ffc6 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/TagHelperOutputExtensionsTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/TagHelperOutputExtensionsTest.cs
@@ -7,6 +7,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.AspNetCore.Razor.TagHelpers;
+using Microsoft.AspNetCore.Razor.TagHelpers.Testing;
 using Microsoft.AspNetCore.Testing;
 using Xunit;
 
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationMessageTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationMessageTagHelperTest.cs
index d704154584..be190e769a 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationMessageTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationMessageTagHelperTest.cs
@@ -324,7 +324,8 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
                 actionContext,
                 Mock.Of<IView>(),
                 new ViewDataDictionary(
-                    new EmptyModelMetadataProvider()),
+                    new EmptyModelMetadataProvider(),
+                    new ModelStateDictionary()),
                 Mock.Of<ITempDataDictionary>(),
                 TextWriter.Null,
                 new HtmlHelperOptions());
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationSummaryTagHelperTest.cs b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationSummaryTagHelperTest.cs
index cb8aa3977d..d4e5b0ede3 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationSummaryTagHelperTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationSummaryTagHelperTest.cs
@@ -14,6 +14,7 @@ using Microsoft.AspNetCore.Mvc.TestCommon;
 using Microsoft.AspNetCore.Mvc.ViewEngines;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Razor.TagHelpers;
+using Microsoft.AspNetCore.Razor.TagHelpers.Testing;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Testing;
 using Moq;
@@ -589,7 +590,8 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
                 actionContext,
                 Mock.Of<IView>(),
                 new ViewDataDictionary(
-                    new EmptyModelMetadataProvider()),
+                    new EmptyModelMetadataProvider(),
+                    new ModelStateDictionary()),
                 Mock.Of<ITempDataDictionary>(),
                 TextWriter.Null,
                 new HtmlHelperOptions());
diff --git a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/project.json b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/project.json
index c19f8eb6f0..35270e6396 100644
--- a/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/project.json
+++ b/test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/project.json
@@ -13,6 +13,10 @@
       "version": "1.1.0-*",
       "type": "build"
     },
+    "Microsoft.AspNetCore.Razor.TagHelpers.Testing.Sources": {
+      "version": "1.1.0-*",
+      "type": "build"
+    },
     "Microsoft.AspNetCore.Testing": "1.1.0-*",
     "Microsoft.DotNet.InternalAbstractions": "1.0.0",
     "Microsoft.Extensions.Logging.Abstractions": "1.1.0-*",