Make HTML helper `null` handling consistent

- #874 lines 3, 4, and 6
- correct `Value()` to treat a `null` expression name the same as `string.Empty`
- add missing `[NotNull]` attributes in `EditorExtensions` and for `GenerateIdFromName()`
- consistently pass `null` for default expression names to the helpers
 - for example, from extension methods
- add test cases using `null` for expression name

nits:
- correct summary XML comment for `HtmlHelper` class
- use named parameters and prefer interface (not extension) methods in changed calls
- use `string.Empty` instead of `""` in a few tests

samples/MvcSample.Web/Views/Shared/EditorTemplates/Decimal.cshtml

@@ -13,6 +13,6 @@
 }
 
 @Html.TextBox(
-    name: string.Empty,
+    name: null,
     value: FormattedValue,
     htmlAttributes: new { @class = "text-box single-line", style = "font-weight: bold", })

src/Microsoft.AspNet.Mvc.Core/Rendering/Html/DefaultEditorTemplates.cs

@@ -32,15 +32,20 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
         private static string BooleanTemplateCheckbox(IHtmlHelper html, bool value)
         {
-            return html.CheckBox(string.Empty, value, CreateHtmlAttributes(html, "check-box")).ToString();
+            return html.CheckBox(
+                name: null,
+                isChecked: value,
+                htmlAttributes: CreateHtmlAttributes(html, "check-box"))
+                    .ToString();
         }
 
         private static string BooleanTemplateDropDownList(IHtmlHelper html, bool? value)
         {
             return html.DropDownList(
-                string.Empty,
+                name: null,
-                DefaultDisplayTemplates.TriStateValues(value),
+                selectList: DefaultDisplayTemplates.TriStateValues(value),
-                CreateHtmlAttributes(html, "list-box tri-state"))
+                optionLabel: null,
+                htmlAttributes: CreateHtmlAttributes(html, "list-box tri-state"))
                     .ToString();
         }
 
@@ -144,7 +149,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
 
             var htmlAttributesObject = viewData[HtmlAttributeKey];
-            var hiddenResult = html.Hidden(string.Empty, model, htmlAttributesObject);
+            var hiddenResult = html.Hidden(name: null, value: model, htmlAttributes: htmlAttributesObject);
             result += hiddenResult.ToString();
 
             return result;
@@ -262,9 +267,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
         public static string PasswordTemplate(IHtmlHelper html)
         {
-            return html.Password(string.Empty,
+            return html.Password(
-                html.ViewData.TemplateInfo.FormattedModelValue,
+                name: null,
-                CreateHtmlAttributes(html, "text-box single-line password"))
+                value: html.ViewData.TemplateInfo.FormattedModelValue,
+                htmlAttributes: CreateHtmlAttributes(html, "text-box single-line password"))
                     .ToString();
         }
 
@@ -356,8 +362,9 @@ namespace Microsoft.AspNet.Mvc.Rendering
         private static string GenerateTextBox(IHtmlHelper html, string inputType, object value)
         {
             return html.TextBox(
-                name: string.Empty,
+                name: null,
                 value: value,
+                format: null,
                 htmlAttributes: CreateHtmlAttributes(html, className: "text-box single-line", inputType: inputType))
                     .ToString();
         }

src/Microsoft.AspNet.Mvc.Core/Rendering/Html/HtmlHelper.cs

@@ -18,7 +18,7 @@ using Microsoft.AspNet.Mvc.Rendering.Expressions;
 namespace Microsoft.AspNet.Mvc.Rendering
 {
     /// <summary>
-    /// Default implementation of non-generic portions of <see cref="IHtmlHelper{TModel}"/>.
+    /// Default implementation of <see cref="IHtmlHelper">.
     /// </summary>
     public class HtmlHelper : IHtmlHelper, ICanHasViewContext
     {
@@ -482,7 +482,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public string Value([NotNull] string name, string format)
+        public string Value(string name, string format)
         {
             return GenerateValue(name, value: null, format: format, useViewData: true);
         }
@@ -1275,7 +1275,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
             else if (useViewData)
             {
-                if (name.Length == 0)
+                if (string.IsNullOrEmpty(name))
                 {
                     // case 2(a): format the value from ModelMetadata for the current model
                     var metadata = ViewData.ModelMetadata;

src/Microsoft.AspNet.Mvc.Core/Rendering/HtmlHelperDisplayExtensions.cs

@@ -90,19 +90,18 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
         public static HtmlString DisplayForModel([NotNull] this IHtmlHelper html)
         {
-            return html.Display(expression: string.Empty, templateName: null, htmlFieldName: null,
+            return html.Display(expression: null, templateName: null, htmlFieldName: null, additionalViewData: null);
-                additionalViewData: null);
         }
 
         public static HtmlString DisplayForModel([NotNull] this IHtmlHelper html, object additionalViewData)
         {
-            return html.Display(expression: string.Empty, templateName: null, htmlFieldName: null,
+            return html.Display(expression: null, templateName: null, htmlFieldName: null,
                 additionalViewData: additionalViewData);
         }
 
         public static HtmlString DisplayForModel([NotNull] this IHtmlHelper html, string templateName)
         {
-            return html.Display(expression: string.Empty, templateName: templateName, htmlFieldName: null,
+            return html.Display(expression: null, templateName: templateName, htmlFieldName: null,
                 additionalViewData: null);
         }
 
@@ -111,7 +110,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             string templateName,
             object additionalViewData)
         {
-            return html.Display(expression: string.Empty, templateName: templateName, htmlFieldName: null,
+            return html.Display(expression: null, templateName: templateName, htmlFieldName: null,
                 additionalViewData: additionalViewData);
         }
 
@@ -120,7 +119,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             string templateName,
             string htmlFieldName)
         {
-            return html.Display(expression: string.Empty, templateName: templateName, htmlFieldName: htmlFieldName,
+            return html.Display(expression: null, templateName: templateName, htmlFieldName: htmlFieldName,
                 additionalViewData: null);
         }
 
@@ -130,7 +129,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             string htmlFieldName,
             object additionalViewData)
         {
-            return html.Display(expression: string.Empty, templateName: templateName, htmlFieldName: htmlFieldName,
+            return html.Display(expression: null, templateName: templateName, htmlFieldName: htmlFieldName,
                 additionalViewData: additionalViewData);
         }
     }

src/Microsoft.AspNet.Mvc.Core/Rendering/HtmlHelperDisplayNameExtensions.cs

@@ -19,7 +19,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <returns>A <see cref="String"/> containing the display name.</returns>
         public static string DisplayNameForModel([NotNull] this IHtmlHelper htmlHelper)
         {
-            return htmlHelper.DisplayName(string.Empty);
+            return htmlHelper.DisplayName(expression: null);
         }
 
         /// <summary>

src/Microsoft.AspNet.Mvc.Core/Rendering/HtmlHelperEditorExtensions.cs

@@ -8,100 +8,101 @@ namespace Microsoft.AspNet.Mvc.Rendering
 {
     public static class EditorExtensions
     {
-        public static HtmlString Editor(this IHtmlHelper html, string expression)
+        public static HtmlString Editor([NotNull] this IHtmlHelper html, string expression)
         {
             return html.Editor(expression, templateName: null, htmlFieldName: null, additionalViewData: null);
         }
 
-        public static HtmlString Editor(this IHtmlHelper html, string expression, object additionalViewData)
+        public static HtmlString Editor([NotNull] this IHtmlHelper html, string expression, object additionalViewData)
         {
             return html.Editor(expression, templateName: null, htmlFieldName: null,
                 additionalViewData: additionalViewData);
         }
 
-        public static HtmlString Editor(this IHtmlHelper html, string expression, string templateName)
+        public static HtmlString Editor([NotNull] this IHtmlHelper html, string expression, string templateName)
         {
             return html.Editor(expression, templateName, htmlFieldName: null, additionalViewData: null);
         }
 
-        public static HtmlString Editor(this IHtmlHelper html, string expression, string templateName,
+        public static HtmlString Editor([NotNull] this IHtmlHelper html, string expression, string templateName,
             object additionalViewData)
         {
             return html.Editor(expression, templateName, htmlFieldName: null, additionalViewData: additionalViewData);
         }
 
-        public static HtmlString Editor(this IHtmlHelper html, string expression, string templateName,
+        public static HtmlString Editor([NotNull] this IHtmlHelper html, string expression, string templateName,
             string htmlFieldName)
         {
             return html.Editor(expression, templateName, htmlFieldName, additionalViewData: null);
         }
 
-        public static HtmlString EditorFor<TModel, TValue>(this IHtmlHelper<TModel> html,
+        public static HtmlString EditorFor<TModel, TValue>([NotNull] this IHtmlHelper<TModel> html,
-            Expression<Func<TModel, TValue>> expression)
+            [NotNull] Expression<Func<TModel, TValue>> expression)
         {
             return html.EditorFor(expression, templateName: null, htmlFieldName: null, additionalViewData: null);
         }
 
-        public static HtmlString EditorFor<TModel, TValue>(this IHtmlHelper<TModel> html,
+        public static HtmlString EditorFor<TModel, TValue>([NotNull] this IHtmlHelper<TModel> html,
-            Expression<Func<TModel, TValue>> expression, object additionalViewData)
+            [NotNull] Expression<Func<TModel, TValue>> expression, object additionalViewData)
         {
             return html.EditorFor(expression, templateName: null, htmlFieldName: null,
                 additionalViewData: additionalViewData);
         }
 
-        public static HtmlString EditorFor<TModel, TValue>(this IHtmlHelper<TModel> html,
+        public static HtmlString EditorFor<TModel, TValue>([NotNull] this IHtmlHelper<TModel> html,
-            Expression<Func<TModel, TValue>> expression, string templateName)
+            [NotNull] Expression<Func<TModel, TValue>> expression, string templateName)
         {
             return html.EditorFor(expression, templateName, htmlFieldName: null, additionalViewData: null);
         }
 
-        public static HtmlString EditorFor<TModel, TValue>(this IHtmlHelper<TModel> html,
+        public static HtmlString EditorFor<TModel, TValue>([NotNull] this IHtmlHelper<TModel> html,
-            Expression<Func<TModel, TValue>> expression, string templateName, object additionalViewData)
+            [NotNull] Expression<Func<TModel, TValue>> expression, string templateName, object additionalViewData)
         {
             return html.EditorFor(expression, templateName, htmlFieldName: null,
                 additionalViewData: additionalViewData);
         }
 
-        public static HtmlString EditorFor<TModel, TValue>(this IHtmlHelper<TModel> html,
+        public static HtmlString EditorFor<TModel, TValue>([NotNull] this IHtmlHelper<TModel> html,
-            Expression<Func<TModel, TValue>> expression, string templateName, string htmlFieldName)
+            [NotNull] Expression<Func<TModel, TValue>> expression, string templateName, string htmlFieldName)
         {
             return html.EditorFor(expression, templateName, htmlFieldName, additionalViewData: null);
         }
 
-        public static HtmlString EditorForModel(this IHtmlHelper html)
+        public static HtmlString EditorForModel([NotNull] this IHtmlHelper html)
         {
-            return html.Editor(expression: string.Empty, templateName: null, htmlFieldName: null,
+            return html.Editor(expression: null, templateName: null, htmlFieldName: null, additionalViewData: null);
-                additionalViewData: null);
         }
 
-        public static HtmlString EditorForModel(this IHtmlHelper html, object additionalViewData)
+        public static HtmlString EditorForModel([NotNull] this IHtmlHelper html, object additionalViewData)
         {
-            return html.Editor(expression: string.Empty, templateName: null, htmlFieldName: null,
+            return html.Editor(expression: null, templateName: null, htmlFieldName: null,
                 additionalViewData: additionalViewData);
         }
 
-        public static HtmlString EditorForModel(this IHtmlHelper html, string templateName)
+        public static HtmlString EditorForModel([NotNull] this IHtmlHelper html, string templateName)
         {
-            return html.Editor(expression: string.Empty, templateName: templateName, htmlFieldName: null,
+            return html.Editor(expression: null, templateName: templateName, htmlFieldName: null,
                 additionalViewData: null);
         }
 
-        public static HtmlString EditorForModel(this IHtmlHelper html, string templateName, object additionalViewData)
+        public static HtmlString EditorForModel([NotNull] this IHtmlHelper html, string templateName,
-        {
-            return html.Editor(expression: string.Empty, templateName: templateName, htmlFieldName: null,
-                additionalViewData: additionalViewData);
-        }
-
-        public static HtmlString EditorForModel(this IHtmlHelper html, string templateName, string htmlFieldName)
-        {
-            return html.Editor(expression: string.Empty, templateName: templateName, htmlFieldName: htmlFieldName,
-                additionalViewData: null);
-        }
-
-        public static HtmlString EditorForModel(this IHtmlHelper html, string templateName, string htmlFieldName,
             object additionalViewData)
         {
-            return html.Editor(expression: string.Empty, templateName: templateName, htmlFieldName: htmlFieldName,
+            return html.Editor(expression: null, templateName: templateName, htmlFieldName: null,
+                additionalViewData: additionalViewData);
+        }
+
+        public static HtmlString EditorForModel([NotNull] this IHtmlHelper html, string templateName,
+            string htmlFieldName)
+        {
+            return html.Editor(expression: null, templateName: templateName, htmlFieldName: htmlFieldName,
+                additionalViewData: null);
+        }
+
+        public static HtmlString EditorForModel([NotNull] this IHtmlHelper html, string templateName,
+            string htmlFieldName, object additionalViewData)
+        {
+            return html.Editor(expression: null, templateName: templateName, htmlFieldName: htmlFieldName,
                 additionalViewData: additionalViewData);
         }
     }

src/Microsoft.AspNet.Mvc.Core/Rendering/HtmlHelperLabelExtensions.cs

@@ -47,12 +47,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
         public static HtmlString LabelForModel([NotNull] this IHtmlHelper html, string labelText)
         {
-            return html.Label(expression: string.Empty, labelText: labelText, htmlAttributes: null);
+            return html.Label(expression: null, labelText: labelText, htmlAttributes: null);
         }
 
         public static HtmlString LabelForModel([NotNull] this IHtmlHelper html, object htmlAttributes)
         {
-            return html.Label(expression: string.Empty, labelText: null, htmlAttributes: htmlAttributes);
+            return html.Label(expression: null, labelText: null, htmlAttributes: htmlAttributes);
         }
 
         public static HtmlString LabelForModel(
@@ -60,7 +60,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             string labelText,
             object htmlAttributes)
         {
-            return html.Label(expression: string.Empty, labelText: labelText, htmlAttributes: htmlAttributes);
+            return html.Label(expression: null, labelText: labelText, htmlAttributes: htmlAttributes);
         }
     }
 }

src/Microsoft.AspNet.Mvc.Core/Rendering/HtmlHelperNameExtensions.cs

@@ -15,7 +15,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <returns>A <see cref="System.String"/> containing the element name.</returns>
         public static string NameForModel([NotNull] this IHtmlHelper htmlHelper)
         {
-            return htmlHelper.Name(string.Empty);
+            return htmlHelper.Name(name: null);
         }
 
         /// <summary>
@@ -25,7 +25,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <returns>A <see cref="System.String"/> containing the element Id.</returns>
         public static string IdForModel([NotNull] this IHtmlHelper htmlHelper)
         {
-            return htmlHelper.Id(string.Empty);
+            return htmlHelper.Id(name: null);
         }
     }
 }

src/Microsoft.AspNet.Mvc.Core/Rendering/HtmlHelperValueExtensions.cs

@@ -53,7 +53,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </remarks>
         public static string ValueForModel([NotNull] this IHtmlHelper htmlHelper)
         {
-            return htmlHelper.Value(name: string.Empty, format: null);
+            return htmlHelper.Value(name: null, format: null);
         }
 
         /// <summary>
@@ -70,7 +70,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </remarks>
         public static string ValueForModel([NotNull] this IHtmlHelper htmlHelper, string format)
         {
-            return htmlHelper.Value(name: string.Empty, format: format);
+            return htmlHelper.Value(name: null, format: format);
         }
     }
 }

src/Microsoft.AspNet.Mvc.Core/Rendering/IHtmlHelper.cs

@@ -236,7 +236,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="name">The name of the HTML element.</param>
         /// <returns>The ID of the HTML element.</returns>
-        string GenerateIdFromName(string name);
+        string GenerateIdFromName([NotNull] string name);
 
         /// <summary>
         /// Returns information about about client validation rules for the given <paramref name="metadata"/> or
@@ -491,6 +491,6 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// Converts the expression result to a <see cref="System.String"/> directly if
         /// <paramref name="format"/> is <c>null</c> or empty.
         /// </remarks>
-        string Value([NotNull] string name, string format);
+        string Value(string name, string format);
     }
 }

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperDisplayNameExtensionsTest.cs

@@ -24,7 +24,7 @@ namespace Microsoft.AspNet.Mvc.Core
                 DefaultTemplatesUtilities.GetHtmlHelper<IEnumerable<DefaultTemplatesUtilities.ObjectTemplateModel>>(null);
 
             // Act
-            var displayNameResult = helper.DisplayName("");
+            var displayNameResult = helper.DisplayName(expression: string.Empty);
             var displayNameNullResult = helper.DisplayName(expression: null);   // null is another alias for current model
             var displayNameForResult = helper.DisplayNameFor(m => m);
             var displayNameForEnumerableModelResult = enumerableHelper.DisplayNameFor(m => m);
@@ -96,7 +96,7 @@ namespace Microsoft.AspNet.Mvc.Core
             enumerableHelper.ViewData.ModelMetadata = metadata;
 
             // Act
-            var displayNameResult = helper.DisplayName("");
+            var displayNameResult = helper.DisplayName(expression: string.Empty);
             var displayNameForResult = helper.DisplayNameFor(m => m);
             var displayNameForEnumerableResult = enumerableHelper.DisplayNameFor(m => m);
             var displayNameForModelResult = helper.DisplayNameForModel();
@@ -153,7 +153,7 @@ namespace Microsoft.AspNet.Mvc.Core
             enumerableHelper.ViewData.ModelMetadata.DisplayName = displayName;
 
             // Act
-            var displayNameResult = helper.DisplayName("");
+            var displayNameResult = helper.DisplayName(expression: string.Empty);
             var displayNameForResult = helper.DisplayNameFor(m => m);
             var displayNameForEnumerableResult = enumerableHelper.DisplayNameFor(m => m);
             var displayNameForModelResult = helper.DisplayNameForModel();

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperDisplayTextTest.cs

@@ -20,7 +20,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var helper = DefaultTemplatesUtilities.GetHtmlHelper<OverriddenToStringModel>(model: null);
 
             // Act
-            var result = helper.DisplayText("");
+            var result = helper.DisplayText(name: string.Empty);
 
             // Assert
             Assert.Empty(result);
@@ -47,7 +47,7 @@ namespace Microsoft.AspNet.Mvc.Core
             helper.ViewData.ModelMetadata.NullDisplayText = "Null display Text";
 
             // Act
-            var result = helper.DisplayText("");
+            var result = helper.DisplayText(name: string.Empty);
 
             // Assert
             Assert.Equal("Null display Text", result);
@@ -75,10 +75,12 @@ namespace Microsoft.AspNet.Mvc.Core
             var helper = DefaultTemplatesUtilities.GetHtmlHelper(model);
 
             // Act
-            var result = helper.DisplayText("");
+            var result = helper.DisplayText(name: string.Empty);
+            var nullResult = helper.DisplayText(name: null);    // null is another alias for current model
 
             // Assert
             Assert.Equal("Model value", result);
+            Assert.Equal("Model value", nullResult);
         }
 
         [Fact]
@@ -118,7 +120,7 @@ namespace Microsoft.AspNet.Mvc.Core
             helper.ViewData.ModelMetadata.SimpleDisplayText = "Simple display text";
 
             // Act
-            var result = helper.DisplayText("");
+            var result = helper.DisplayText(name: string.Empty);
 
             // Assert
             Assert.Equal("Simple display text", result);

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperLabelExtensionsTest.cs

@@ -22,7 +22,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var helper = DefaultTemplatesUtilities.GetHtmlHelper();
 
             // Act
-            var labelResult = helper.Label("");
+            var labelResult = helper.Label(expression: string.Empty);
             var labelNullResult = helper.Label(expression: null);   // null is another alias for current model
             var labelForResult = helper.LabelFor(m => m);
             var labelForModelResult = helper.LabelForModel();
@@ -79,7 +79,7 @@ namespace Microsoft.AspNet.Mvc.Core
             helper.ViewData.ModelMetadata = metadata;
 
             // Act
-            var labelResult = helper.Label("");
+            var labelResult = helper.Label(expression: string.Empty);
             var labelNullResult = helper.Label(expression: null);   // null is another alias for current model
             var labelForResult = helper.LabelFor(m => m);
             var labelForModelResult = helper.LabelForModel();
@@ -108,7 +108,7 @@ namespace Microsoft.AspNet.Mvc.Core
             helper.ViewData.ModelMetadata = metadata;
 
             // Act
-            var labelResult = helper.Label("");
+            var labelResult = helper.Label(expression: string.Empty);
             var labelForResult = helper.LabelFor(m => m);
             var labelForModelResult = helper.LabelForModel();
 
@@ -152,7 +152,7 @@ namespace Microsoft.AspNet.Mvc.Core
             helper.ViewData.ModelMetadata.DisplayName = string.Empty;
 
             // Act
-            var labelResult = helper.Label("");
+            var labelResult = helper.Label(expression: string.Empty);
             var labelNullResult = helper.Label(expression: null);   // null is another alias for current model
             var labelForResult = helper.LabelFor(m => m);
             var labelForModelResult = helper.LabelForModel();
@@ -174,7 +174,7 @@ namespace Microsoft.AspNet.Mvc.Core
             helper.ViewData.ModelMetadata.DisplayName = displayName;
 
             // Act
-            var labelResult = helper.Label("");
+            var labelResult = helper.Label(expression: string.Empty);
             var labelForResult = helper.LabelFor(m => m);
             var labelForModelResult = helper.LabelForModel();
 
@@ -195,7 +195,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var helper = DefaultTemplatesUtilities.GetHtmlHelper(metadataHelper.MetadataProvider.Object);
 
             // Act
-            var labelResult = helper.Label("");
+            var labelResult = helper.Label(expression: string.Empty);
             var labelNullResult = helper.Label(expression: null);   // null is another alias for current model
             var labelForResult = helper.LabelFor(m => m);
             var labelForModelResult = helper.LabelForModel();

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperNameExtensionsTest.cs

@@ -25,11 +25,11 @@ namespace Microsoft.AspNet.Mvc.Core
             var helper = DefaultTemplatesUtilities.GetHtmlHelper();
 
             // Act
-            var idResult = helper.Id("");
+            var idResult = helper.Id(name: string.Empty);
             var idNullResult = helper.Id(name: null);   // null is another alias for current model
             var idForResult = helper.IdFor(m => m);
             var idForModelResult = helper.IdForModel();
-            var nameResult = helper.Name("");
+            var nameResult = helper.Name(name: string.Empty);
             var nameNullResult = helper.Name(name: null);
             var nameForResult = helper.NameFor(m => m);
             var nameForModelResult = helper.NameForModel();
@@ -58,10 +58,10 @@ namespace Microsoft.AspNet.Mvc.Core
             helper.ViewData.TemplateInfo.HtmlFieldPrefix = prefix;
 
             // Act
-            var idResult = helper.Id("");
+            var idResult = helper.Id(name: string.Empty);
             var idForResult = helper.IdFor(m => m);
             var idForModelResult = helper.IdForModel();
-            var nameResult = helper.Name("");
+            var nameResult = helper.Name(name: string.Empty);
             var nameForResult = helper.NameFor(m => m);
             var nameForModelResult = helper.NameForModel();
 
@@ -152,10 +152,10 @@ namespace Microsoft.AspNet.Mvc.Core
             var helper = DefaultTemplatesUtilities.GetHtmlHelper(provider.Object);
 
             // Act (do not throw)
-            var idResult = helper.Id("");
+            var idResult = helper.Id(name: string.Empty);
             var idForResult = helper.IdFor(m => m);
             var idForModelResult = helper.IdForModel();
-            var nameResult = helper.Name("");
+            var nameResult = helper.Name(name: string.Empty);
             var nameForResult = helper.NameFor(m => m);
             var nameForModelResult = helper.NameForModel();
 

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperValueExtensionsTest.cs

@@ -94,6 +94,7 @@ namespace Microsoft.AspNet.Mvc.Core
 
             // Act & Assert
             Assert.Equal(expectedModelValue, helper.Value(name: string.Empty));
+            Assert.Equal(expectedModelValue, helper.Value(name: null)); // null is another alias for current model
             Assert.Equal(expectedModelValue, helper.ValueFor(m => m));
             Assert.Equal(expectedModelValue, helper.ValueForModel());
         }