2721: Fixing the error message for empty html field name

src/Microsoft.AspNet.Mvc.ViewFeatures/Properties/Resources.Designer.cs

@@ -762,6 +762,22 @@ namespace Microsoft.AspNet.Mvc.ViewFeatures
             return string.Format(CultureInfo.CurrentCulture, GetString("RemoteAttribute_RemoteValidationFailed"), p0);
         }
 
+        /// <summary>
+        /// The name of an HTML field cannot be null or empty. Instead use methods {0}.{1} or {2}.{3} with a non-empty {4} argument value.
+        /// </summary>
+        internal static string HtmlGenerator_FieldNameCannotBeNullOrEmpty
+        {
+            get { return GetString("HtmlGenerator_FieldNameCannotBeNullOrEmpty"); }
+        }
+
+        /// <summary>
+        /// The name of an HTML field cannot be null or empty. Instead use methods {0}.{1} or {2}.{3} with a non-empty {4} argument value.
+        /// </summary>
+        internal static string FormatHtmlGenerator_FieldNameCannotBeNullOrEmpty(object p0, object p1, object p2, object p3, object p4)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("HtmlGenerator_FieldNameCannotBeNullOrEmpty"), p0, p1, p2, p3, p4);
+        }
+
         private static string GetString(string name, params string[] formatterNames)
         {
             var value = _resourceManager.GetString(name);

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Html/DefaultHtmlGenerator.cs

@@ -413,8 +413,15 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var fullName = GetFullHtmlFieldName(viewContext, expression);
             if (string.IsNullOrEmpty(fullName))
             {
-                throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(expression));
+                throw new ArgumentException(
-            }
+                    Resources.FormatHtmlGenerator_FieldNameCannotBeNullOrEmpty(
+                        typeof(IHtmlHelper).FullName,
+                        nameof(IHtmlHelper.Editor),
+                        typeof(IHtmlHelper<>).FullName,
+                        nameof(IHtmlHelper<object>.EditorFor),
+                        "htmlFieldName"),
+                    nameof(expression));
+        }
 
             // If we got a null selectList, try to use ViewData to get the list of items.
             if (selectList == null)
@@ -483,7 +490,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var fullName = GetFullHtmlFieldName(viewContext, expression);
             if (string.IsNullOrEmpty(fullName))
             {
-                throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(expression));
+                throw new ArgumentException(
+                    Resources.FormatHtmlGenerator_FieldNameCannotBeNullOrEmpty(
+                        typeof(IHtmlHelper).FullName,
+                        nameof(IHtmlHelper.Editor),
+                        typeof(IHtmlHelper<>).FullName,
+                        nameof(IHtmlHelper<object>.EditorFor),
+                        "htmlFieldName"),
+                    nameof(expression));
             }
 
             ModelState modelState;
@@ -563,7 +577,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var fullName = GetFullHtmlFieldName(viewContext, expression);
             if (string.IsNullOrEmpty(fullName))
             {
-                throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(expression));
+                throw new ArgumentException(
+                    Resources.FormatHtmlGenerator_FieldNameCannotBeNullOrEmpty(
+                        typeof(IHtmlHelper).FullName,
+                        nameof(IHtmlHelper.Editor),
+                        typeof(IHtmlHelper<>).FullName,
+                        nameof(IHtmlHelper<object>.EditorFor),
+                        "htmlFieldName"),
+                    nameof(expression));
             }
 
             var formContext = viewContext.ClientValidationEnabled ? viewContext.FormContext : null;
@@ -738,7 +759,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var fullName = GetFullHtmlFieldName(viewContext, expression);
             if (string.IsNullOrEmpty(fullName))
             {
-                throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(expression));
+                throw new ArgumentException(
+                    Resources.FormatHtmlGenerator_FieldNameCannotBeNullOrEmpty(
+                        typeof(IHtmlHelper).FullName,
+                        nameof(IHtmlHelper.Editor),
+                        typeof(IHtmlHelper<>).FullName,
+                        nameof(IHtmlHelper<object>.EditorFor),
+                        "htmlFieldName"),
+                    nameof(expression));
             }
 
             var type = allowMultiple ? typeof(string[]) : typeof(string);
@@ -969,7 +997,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var fullName = GetFullHtmlFieldName(viewContext, expression);
             if (string.IsNullOrEmpty(fullName))
             {
-                throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(expression));
+                throw new ArgumentException(
+                    Resources.FormatHtmlGenerator_FieldNameCannotBeNullOrEmpty(
+                        typeof(IHtmlHelper).FullName,
+                        nameof(IHtmlHelper.Editor),
+                        typeof(IHtmlHelper<>).FullName,
+                        nameof(IHtmlHelper<object>.EditorFor),
+                        "htmlFieldName"),
+                    nameof(expression));
             }
 
             var tagBuilder = new TagBuilder("input", _htmlEncoder);

src/Microsoft.AspNet.Mvc.ViewFeatures/Resources.resx

@@ -259,4 +259,7 @@
   <data name="RemoteAttribute_RemoteValidationFailed" xml:space="preserve">
     <value>'{0}' is invalid.</value>
   </data>
+  <data name="HtmlGenerator_FieldNameCannotBeNullOrEmpty" xml:space="preserve">
+    <value>The name of an HTML field cannot be null or empty. Instead use methods {0}.{1} or {2}.{3} with a non-empty {4} argument value.</value>
+  </data>
 </root>

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/DefaultHtmlGeneratorTest.cs

@@ -60,6 +60,116 @@ namespace Microsoft.AspNet.Mvc.Rendering
             Assert.Null(result);
         }
 
+        [Fact]
+        public void GetCurrentValues_WithNullExpression_Throws()
+        {
+            // Arrange
+            var metadataProvider = new TestModelMetadataProvider();
+            var htmlGenerator = GetGenerator(metadataProvider);
+            var viewContext = GetViewContext<Model>(model: null, metadataProvider: metadataProvider);
+            var modelExplorer = metadataProvider.GetModelExplorerForType(typeof(string), model: null);
+
+            var expected = "The name of an HTML field cannot be null or empty. Instead use methods " + 
+                "Microsoft.AspNet.Mvc.Rendering.IHtmlHelper.Editor or Microsoft.AspNet.Mvc.Rendering." + 
+                "IHtmlHelper`1.EditorFor with a non-empty htmlFieldName argument value." +
+                Environment.NewLine + "Parameter name: expression";
+
+            // Act and assert
+            var ex = Assert.Throws<ArgumentException>(
+                "expression",
+                () => htmlGenerator.GetCurrentValues(
+                    viewContext,
+                    modelExplorer,
+                    expression: null,
+                    allowMultiple: true));
+
+            Assert.Equal(expected, ex.Message);
+        }
+
+        [Fact]
+        public void GenerateSelect_WithNullExpression_Throws()
+        {
+            // Arrange
+            var metadataProvider = new TestModelMetadataProvider();
+            var htmlGenerator = GetGenerator(metadataProvider);
+            var viewContext = GetViewContext<Model>(model: null, metadataProvider: metadataProvider);
+            var modelExplorer = metadataProvider.GetModelExplorerForType(typeof(string), model: null);
+
+            var expected = "The name of an HTML field cannot be null or empty. Instead use methods " +
+                "Microsoft.AspNet.Mvc.Rendering.IHtmlHelper.Editor or Microsoft.AspNet.Mvc.Rendering." +
+                "IHtmlHelper`1.EditorFor with a non-empty htmlFieldName argument value." +
+                Environment.NewLine + "Parameter name: expression";
+
+            // Act and assert
+            var ex = Assert.Throws<ArgumentException>(
+                "expression",
+                () => htmlGenerator.GenerateSelect(
+                    viewContext,
+                    modelExplorer,
+                    "label",
+                    null,
+                    new List<SelectListItem>(),
+                    true,
+                    null));
+
+            Assert.Equal(expected, ex.Message);
+        }
+
+        [Fact]
+        public void GenerateTextArea_WithNullExpression_Throws()
+        {
+            // Arrange
+            var metadataProvider = new TestModelMetadataProvider();
+            var htmlGenerator = GetGenerator(metadataProvider);
+            var viewContext = GetViewContext<Model>(model: null, metadataProvider: metadataProvider);
+            var modelExplorer = metadataProvider.GetModelExplorerForType(typeof(string), model: null);
+
+            var expected = "The name of an HTML field cannot be null or empty. Instead use methods " +
+                "Microsoft.AspNet.Mvc.Rendering.IHtmlHelper.Editor or Microsoft.AspNet.Mvc.Rendering." +
+                "IHtmlHelper`1.EditorFor with a non-empty htmlFieldName argument value." +
+                Environment.NewLine + "Parameter name: expression";
+
+            // Act and assert
+            var ex = Assert.Throws<ArgumentException>(
+                "expression", 
+                () => htmlGenerator.GenerateTextArea(
+                    viewContext,
+                    modelExplorer,
+                    null,
+                    1,
+                    1,
+                    null));
+
+            Assert.Equal(expected, ex.Message);
+        }
+
+        [Fact]
+        public void GenerateValidationMessage_WithNullExpression_Throws()
+        {
+            // Arrange
+            var metadataProvider = new TestModelMetadataProvider();
+            var htmlGenerator = GetGenerator(metadataProvider);
+            var viewContext = GetViewContext<Model>(model: null, metadataProvider: metadataProvider);
+            var modelExplorer = metadataProvider.GetModelExplorerForType(typeof(string), model: null);
+
+            var expected = "The name of an HTML field cannot be null or empty. Instead use methods " +
+                "Microsoft.AspNet.Mvc.Rendering.IHtmlHelper.Editor or Microsoft.AspNet.Mvc.Rendering." +
+                "IHtmlHelper`1.EditorFor with a non-empty htmlFieldName argument value." +
+                Environment.NewLine + "Parameter name: expression";
+
+            // Act and assert
+            var ex = Assert.Throws<ArgumentException>(
+                "expression", 
+                () => htmlGenerator.GenerateValidationMessage(
+                    viewContext,
+                    null,
+                    "Message",
+                    "tag",
+                    null));
+
+            Assert.Equal(expected, ex.Message);
+        }
+
         [Theory]
         [InlineData(false)]
         [InlineData(true)]

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperCheckboxTest.cs

@@ -86,6 +86,25 @@ namespace Microsoft.AspNet.Mvc.Rendering
             Assert.Equal(expected, ex.Message);
         }
 
+        [Fact]
+        public void CheckBoxWithNullExpressionThrows()
+        {
+            // Arrange
+            var expected = "The name of an HTML field cannot be null or empty. Instead use methods " +
+                "Microsoft.AspNet.Mvc.Rendering.IHtmlHelper.Editor or Microsoft.AspNet.Mvc.Rendering." +
+                "IHtmlHelper`1.EditorFor with a non-empty htmlFieldName argument value." +
+                Environment.NewLine + "Parameter name: expression";
+
+            var helper = DefaultTemplatesUtilities.GetHtmlHelper(GetTestModelViewData());
+
+            // Act & Assert
+            var ex = Assert.Throws<ArgumentException>(
+                "expression",
+                () => helper.CheckBox(null, isChecked: true, htmlAttributes: null));
+
+            Assert.Equal(expected, ex.Message);
+        }
+
         [Fact]
         public void CheckBoxCheckedWithOnlyName_GeneratesExpectedValue()
         {

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperHiddenTest.cs

@@ -403,10 +403,16 @@ namespace Microsoft.AspNet.Mvc.Rendering
             {
                 { "class", "some-class"}
             };
+            var expected = "The name of an HTML field cannot be null or empty. Instead use methods " +
+                "Microsoft.AspNet.Mvc.Rendering.IHtmlHelper.Editor or Microsoft.AspNet.Mvc.Rendering." +
+                "IHtmlHelper`1.EditorFor with a non-empty htmlFieldName argument value." +
+                Environment.NewLine + "Parameter name: expression";
 
             // Act and Assert
-            ExceptionAssert.ThrowsArgumentNullOrEmpty(() => helper.Hidden(string.Empty, string.Empty, attributes),
+            ExceptionAssert.ThrowsArgument(
-                                                      "expression");
+                () => helper.Hidden(string.Empty, string.Empty, attributes), 
+                "expression",
+                expected);
         }
 
         [Fact]

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperPasswordTest.cs

@@ -128,10 +128,16 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var helper = DefaultTemplatesUtilities.GetHtmlHelper(GetViewDataWithModelStateAndModelAndViewDataValues());
             var name = string.Empty;
             var value = string.Empty;
+            var expected = "The name of an HTML field cannot be null or empty. Instead use methods " +
+                "Microsoft.AspNet.Mvc.Rendering.IHtmlHelper.Editor or Microsoft.AspNet.Mvc.Rendering." +
+                "IHtmlHelper`1.EditorFor with a non-empty htmlFieldName argument value." +
+                Environment.NewLine + "Parameter name: expression";
 
             // Act and Assert
-            ExceptionAssert.ThrowsArgumentNullOrEmpty(() => helper.Password(name, value, htmlAttributes: null),
+            ExceptionAssert.ThrowsArgument(
-                                                      "expression");
+                () => helper.Password(name, value, htmlAttributes: null),
+                "expression",
+                expected);
         }
 
         [Fact]

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperSelectTest.cs

@@ -362,6 +362,27 @@ namespace Microsoft.AspNet.Mvc.Rendering
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
+        [Theory]
+        [MemberData(nameof(DropDownListDataSet))]
+        public void DropDownList_WithNullExpression_Throws(
+            IEnumerable<SelectListItem> selectList,
+            string expectedHtml,
+            string ignoredHtml)
+        {
+            // Arrange
+            var expected = "The name of an HTML field cannot be null or empty. Instead use methods " +
+                "Microsoft.AspNet.Mvc.Rendering.IHtmlHelper.Editor or Microsoft.AspNet.Mvc.Rendering." +
+                "IHtmlHelper`1.EditorFor with a non-empty htmlFieldName argument value." +
+                Environment.NewLine + "Parameter name: expression";
+            var helper = DefaultTemplatesUtilities.GetHtmlHelper();
+
+            // Act & Assert
+            var ex = Assert.Throws<ArgumentException>(
+                "expression", 
+                () => helper.DropDownList(null, selectList: null, optionLabel: null, htmlAttributes: null));
+            Assert.Equal(expected, ex.Message);
+        }
+
         [Theory]
         [MemberData(nameof(DropDownListDataSet))]
         public void DropDownList_WithModelValue_GeneratesExpectedValue(