Do not generate a validation summary when `excludePropertyErrors` unless specific model has an error

- #5209
- update affected `HtmlHelperValiationSummaryTest` and functional tests
- add `ValidationSummaryTagHelperTest` tests to cover related scenarios

##### Behaviour changes when no errors exist for the model:
###### Tag helper
``` html
<div asp-validation-summary="ModelOnly" class="order"><h3>Oopsie<h3></div>
```
previously generated
``` html
<div class="order validation-summary-errors"><h3>Oopsie</h3><ul><li style="display:none"></li>
</ul></div>
```
and now generates
``` html
<div class="order"><h3>Oopsie</h3></div>
```
###### HTML helper
``` c#
@Html.ValidationSummary(excludePropertyErrors: true, message: "Oopsie")
```
previously generated
``` html
<div class=\"validation-summary-errors\"><span>Oopsie</span>
<ul><li style=\"display:none\"></li>
</ul></div>
```
and now generates nothing (`@HtmlString.Empty`).

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewFeatures/DefaultHtmlGenerator.cs

@@ -816,9 +816,19 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
                 throw new ArgumentNullException(nameof(viewContext));
             }
 
-            if (viewContext.ViewData.ModelState.IsValid && (!viewContext.ClientValidationEnabled || excludePropertyErrors))
+            var viewData = viewContext.ViewData;
+            if (!viewContext.ClientValidationEnabled && viewData.ModelState.IsValid)
             {
-                // No client side validation/updates
+                // Client-side validation is not enabled to add to the generated element and element will be empty.
+                return null;
+            }
+
+            ModelStateEntry entryForModel;
+            if (excludePropertyErrors &&
+                (!viewData.ModelState.TryGetValue(viewData.TemplateInfo.HtmlFieldPrefix, out entryForModel) ||
+                 entryForModel.Errors.Count == 0))
+            {
+                // Client-side validation (if enabled) will not affect the generated element and element will be empty.
                 return null;
             }
 
@@ -829,6 +839,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
                 {
                     headerTag = viewContext.ValidationSummaryMessageElement;
                 }
+
                 var messageTag = new TagBuilder(headerTag);
                 messageTag.InnerHtml.SetContent(message);
                 wrappedMessage.AppendLine(messageTag);
@@ -841,7 +852,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
             // If excludePropertyErrors is true, describe any validation issue with the current model in a single item.
             // Otherwise, list individual property errors.
             var isHtmlSummaryModified = false;
-            var modelStates = ValidationHelpers.GetModelStateList(viewContext.ViewData, excludePropertyErrors);
+            var modelStates = ValidationHelpers.GetModelStateList(viewData, excludePropertyErrors);
 
             var htmlSummary = new TagBuilder("ul");
             foreach (var modelState in modelStates)
@@ -871,7 +882,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
             var tagBuilder = new TagBuilder("div");
             tagBuilder.MergeAttributes(GetHtmlAttributeDictionaryOrNull(htmlAttributes));
 
-            if (viewContext.ViewData.ModelState.IsValid)
+            if (viewData.ModelState.IsValid)
             {
                 tagBuilder.AddCssClass(HtmlHelper.ValidationSummaryValidCssClassName);
             }

test/Microsoft.AspNetCore.Mvc.FunctionalTests/HtmlHelperOptionsTest.cs

@@ -23,7 +23,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             // Arrange
             var expected =
 @"<div class=""validation-summary-errors""><validationSummaryElement>MySummary</validationSummaryElement>
-<ul><li style=""display:none""></li>
+<ul><li>A model error occurred.</li>
 </ul></div>
 <validationMessageElement class=""field-validation-error"">An error occurred.</validationMessageElement>
 <input id=""Prefix!Property1"" name=""Prefix.Property1"" type=""text"" value="""" />
@@ -31,7 +31,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
 <div class=""editor-field""><input class=""text-box single-line"" id=""MyDate"" name=""MyDate"" type=""datetime"" value=""2000-01-02T03:04:05.060&#x2B;00:00"" /> </div>
 
 <div class=""validation-summary-errors""><validationSummaryElement>MySummary</validationSummaryElement>
-<ul><li style=""display:none""></li>
+<ul><li>A model error occurred.</li>
 </ul></div>
 <validationMessageElement class=""field-validation-error"">An error occurred.</validationMessageElement>
 <input id=""Prefix!Property1"" name=""Prefix.Property1"" type=""text"" value="""" />
@@ -54,7 +54,7 @@ False";
             // Arrange
             var expected =
 @"<div class=""validation-summary-errors""><ValidationSummaryInView>MySummary</ValidationSummaryInView>
-<ul><li style=""display:none""></li>
+<ul><li>A model error occurred.</li>
 </ul></div>
 <ValidationInView class=""field-validation-error"" data-valmsg-for=""Error"" data-valmsg-replace=""true"">An error occurred.</ValidationInView>
 <input id=""Prefix!Property1"" name=""Prefix.Property1"" type=""text"" value="""" />
@@ -63,7 +63,7 @@ False";
 
 True
 <div class=""validation-summary-errors""><ValidationSummaryInPartialView>MySummary</ValidationSummaryInPartialView>
-<ul><li style=""display:none""></li>
+<ul><li>A model error occurred.</li>
 </ul></div>
 <ValidationInPartialView class=""field-validation-error"" data-valmsg-for=""Error"" data-valmsg-replace=""true"">An error occurred.</ValidationInPartialView>
 <input id=""Prefix!Property1"" name=""Prefix.Property1"" type=""text"" value="""" />

test/Microsoft.AspNetCore.Mvc.FunctionalTests/compiler/resources/HtmlGenerationWebSite.HtmlGeneration_Customer.Index.html

@@ -33,8 +33,7 @@
         <div class="order validation-summary-errors" data-valmsg-summary="true"><ul><li>The value &#x27;&#x27; is invalid.</li>
 <li>The Password field is required.</li>
 </ul></div>
-        <div class="order validation-summary-errors"><ul><li style="display:none"></li>
+        <div class="order"></div>
-</ul></div>
         <input type="submit"/>
     <input name="__RequestVerificationToken" type="hidden" value="{0}" /></form>
 </body>

test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/ValidationSummaryTagHelperTest.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Html;
 using Microsoft.AspNetCore.Http;
@@ -42,8 +41,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
 
         [Theory]
         [MemberData(nameof(ProcessAsync_GeneratesExpectedOutput_WithNoErrorsData))]
-        public async Task ProcessAsync_GeneratesExpectedOutput_WithNoErrors(
+        public async Task ProcessAsync_GeneratesExpectedOutput_WithNoErrors(ModelStateDictionary modelState)
-            ModelStateDictionary modelState)
         {
             // Arrange
             var expectedTagName = "not-div";
@@ -53,8 +51,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             var expectedPreContent = "original pre-content";
             var expectedContent = "original content";
             var tagHelperContext = new TagHelperContext(
-                allAttributes: new TagHelperAttributeList(
+                allAttributes: new TagHelperAttributeList(),
-                    Enumerable.Empty<TagHelperAttribute>()),
                 items: new Dictionary<object, object>(),
                 uniqueId: "test");
             var output = new TagHelperOutput(
@@ -65,9 +62,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
                 },
                 getChildContentAsync: (useCachedResult, encoder) =>
                 {
-                    var tagHelperContent = new DefaultTagHelperContent();
+                    throw new InvalidOperationException("getChildContentAsync called unexpectedly");
-                    tagHelperContent.SetContent("Something");
-                    return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
@@ -85,11 +80,18 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             await validationSummaryTagHelper.ProcessAsync(tagHelperContext, output);
 
             // Assert
-            Assert.Equal(2, output.Attributes.Count);
+            Assert.Collection(
-            var attribute = Assert.Single(output.Attributes, attr => attr.Name.Equals("class"));
+                output.Attributes,
-            Assert.Equal("form-control validation-summary-valid", attribute.Value);
+                attribute =>
-            attribute = Assert.Single(output.Attributes, attr => attr.Name.Equals("data-valmsg-summary"));
+                {
-            Assert.Equal("true", attribute.Value);
+                    Assert.Equal("class", attribute.Name);
+                    Assert.Equal("form-control validation-summary-valid", attribute.Value);
+                },
+                attribute =>
+                {
+                    Assert.Equal("data-valmsg-summary", attribute.Name);
+                    Assert.Equal("true", attribute.Value);
+                });
             Assert.Equal(expectedPreContent, output.PreContent.GetContent());
             Assert.Equal(expectedContent, output.Content.GetContent());
             Assert.Equal(
@@ -98,6 +100,120 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             Assert.Equal(expectedTagName, output.TagName);
         }
 
+        [Theory]
+        [MemberData(nameof(ProcessAsync_GeneratesExpectedOutput_WithNoErrorsData))]
+        public async Task ProcessAsync_DoesNothingIfClientSideValiationDisabled_WithNoErrorsData(
+            ModelStateDictionary modelStateDictionary)
+        {
+            // Arrange
+            var metadataProvider = new TestModelMetadataProvider();
+            var htmlGenerator = new TestableHtmlGenerator(metadataProvider);
+            var viewContext = CreateViewContext();
+            viewContext.ClientValidationEnabled = false;
+
+            var validationSummaryTagHelper = new ValidationSummaryTagHelper(htmlGenerator)
+            {
+                ValidationSummary = ValidationSummary.All,
+                ViewContext = viewContext,
+            };
+
+            var output = new TagHelperOutput(
+                "div",
+                new TagHelperAttributeList(),
+                (useCachedResult, encoder) =>
+                {
+                    throw new InvalidOperationException("getChildContentAsync called unexpectedly.");
+                });
+
+            var context = new TagHelperContext(
+                new TagHelperAttributeList(),
+                items: new Dictionary<object, object>(),
+                uniqueId: "test");
+
+            // Act
+            await validationSummaryTagHelper.ProcessAsync(context, output);
+
+            // Assert
+            Assert.Equal("div", output.TagName);
+            Assert.Empty(output.Attributes);
+            Assert.False(output.IsContentModified);
+            Assert.False(output.PreContent.IsModified);
+            Assert.False(output.PreElement.IsModified);
+            Assert.False(output.PostContent.IsModified);
+            Assert.False(output.PostElement.IsModified);
+        }
+
+        public static TheoryData<string, ModelStateDictionary> ProcessAsync_DoesNothingIfModelOnly_WithNoModelErrorData
+        {
+            get
+            {
+                var emptyModelState = new ModelStateDictionary();
+
+                var modelState = new ModelStateDictionary();
+                SetValidModelState(modelState);
+
+                var invalidModelState = new ModelStateDictionary();
+                SetValidModelState(invalidModelState);
+                invalidModelState.AddModelError($"{nameof(Model.Strings)}[1]", "This value is invalid.");
+
+                return new TheoryData<string, ModelStateDictionary>
+                {
+                    { string.Empty, emptyModelState },
+                    { string.Empty, modelState },
+                    { nameof(Model.Text), modelState },
+                    { "not-a-key", modelState },
+                    { string.Empty, invalidModelState },
+                    { $"{nameof(Model.Strings)}[2]", invalidModelState },
+                    { nameof(Model.Text), invalidModelState },
+                    { "not-a-key", invalidModelState },
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(ProcessAsync_DoesNothingIfModelOnly_WithNoModelErrorData))]
+        public async Task ProcessAsync_DoesNothingIfModelOnly_WithNoModelError(
+            string prefix,
+            ModelStateDictionary modelStateDictionary)
+        {
+            // Arrange
+            var metadataProvider = new TestModelMetadataProvider();
+            var htmlGenerator = new TestableHtmlGenerator(metadataProvider);
+            var viewContext = CreateViewContext();
+            viewContext.ViewData.TemplateInfo.HtmlFieldPrefix = prefix;
+
+            var validationSummaryTagHelper = new ValidationSummaryTagHelper(htmlGenerator)
+            {
+                ValidationSummary = ValidationSummary.ModelOnly,
+                ViewContext = viewContext,
+            };
+
+            var output = new TagHelperOutput(
+                "div",
+                new TagHelperAttributeList(),
+                (useCachedResult, encoder) =>
+                {
+                    throw new InvalidOperationException("getChildContentAsync called unexpectedly.");
+                });
+
+            var context = new TagHelperContext(
+                new TagHelperAttributeList(),
+                items: new Dictionary<object, object>(),
+                uniqueId: "test");
+
+            // Act
+            await validationSummaryTagHelper.ProcessAsync(context, output);
+
+            // Assert
+            Assert.Equal("div", output.TagName);
+            Assert.Empty(output.Attributes);
+            Assert.False(output.IsContentModified);
+            Assert.False(output.PreContent.IsModified);
+            Assert.False(output.PreElement.IsModified);
+            Assert.False(output.PostContent.IsModified);
+            Assert.False(output.PostElement.IsModified);
+        }
+
         [Theory]
         [InlineData(ValidationSummary.All)]
         [InlineData(ValidationSummary.ModelOnly)]
@@ -117,8 +233,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             var expectedPreContent = "original pre-content";
             var expectedContent = "original content";
             var tagHelperContext = new TagHelperContext(
-                allAttributes: new TagHelperAttributeList(
+                allAttributes: new TagHelperAttributeList(),
-                    Enumerable.Empty<TagHelperAttribute>()),
                 items: new Dictionary<object, object>(),
                 uniqueId: "test");
             var output = new TagHelperOutput(
@@ -178,8 +293,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             var expectedPreContent = "original pre-content";
             var expectedContent = "original content";
             var tagHelperContext = new TagHelperContext(
-                allAttributes: new TagHelperAttributeList(
+                allAttributes: new TagHelperAttributeList(),
-                    Enumerable.Empty<TagHelperAttribute>()),
                 items: new Dictionary<object, object>(),
                 uniqueId: "test");
             var output = new TagHelperOutput(
@@ -211,11 +325,18 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             await validationSummaryTagHelper.ProcessAsync(tagHelperContext, output);
 
             // Assert
-            Assert.Equal(2, output.Attributes.Count);
+            Assert.Collection(
-            var attribute = Assert.Single(output.Attributes, attr => attr.Name.Equals("class"));
+                output.Attributes,
-            Assert.Equal("form-control validation-summary-errors", attribute.Value);
+                attribute =>
-            attribute = Assert.Single(output.Attributes, attr => attr.Name.Equals("data-valmsg-summary"));
+                {
-            Assert.Equal("true", attribute.Value);
+                    Assert.Equal("class", attribute.Name);
+                    Assert.Equal("form-control validation-summary-errors", attribute.Value);
+                },
+                attribute =>
+                {
+                    Assert.Equal("data-valmsg-summary", attribute.Name);
+                    Assert.Equal("true", attribute.Value);
+                });
             Assert.Equal(expectedPreContent, output.PreContent.GetContent());
             Assert.Equal(expectedContent, output.Content.GetContent());
             Assert.Equal(
@@ -266,8 +387,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             validationSummaryTagHelper.ViewContext = expectedViewContext;
 
             var context = new TagHelperContext(
-                allAttributes: new TagHelperAttributeList(
+                allAttributes: new TagHelperAttributeList(),
-                    Enumerable.Empty<TagHelperAttribute>()),
                 items: new Dictionary<object, object>(),
                 uniqueId: "test");
 
@@ -288,9 +408,9 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             // Arrange
             var tagBuilder = new TagBuilder("span2");
             tagBuilder.InnerHtml.SetHtmlContent("New HTML");
+            tagBuilder.Attributes.Add("anything", "something");
             tagBuilder.Attributes.Add("data-foo", "bar");
             tagBuilder.Attributes.Add("data-hello", "world");
-            tagBuilder.Attributes.Add("anything", "something");
 
             var generator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             generator
@@ -322,8 +442,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             validationSummaryTagHelper.ViewContext = viewContext;
 
             var context = new TagHelperContext(
-                allAttributes: new TagHelperAttributeList(
+                allAttributes: new TagHelperAttributeList(),
-                    Enumerable.Empty<TagHelperAttribute>()),
                 items: new Dictionary<object, object>(),
                 uniqueId: "test");
 
@@ -332,13 +451,23 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
 
             // Assert
             Assert.Equal("div", output.TagName);
-            Assert.Equal(3, output.Attributes.Count);
+            Assert.Collection(
-            var attribute = Assert.Single(output.Attributes, attr => attr.Name.Equals("data-foo"));
+                output.Attributes,
-            Assert.Equal("bar", attribute.Value);
+                attribute =>
-            attribute = Assert.Single(output.Attributes, attr => attr.Name.Equals("data-hello"));
+                {
-            Assert.Equal("world", attribute.Value);
+                    Assert.Equal("anything", attribute.Name);
-            attribute = Assert.Single(output.Attributes, attr => attr.Name.Equals("anything"));
+                    Assert.Equal("something", attribute.Value);
-            Assert.Equal("something", attribute.Value);
+                },
+                attribute =>
+                {
+                    Assert.Equal("data-foo", attribute.Name);
+                    Assert.Equal("bar", attribute.Value);
+                },
+                attribute =>
+                {
+                    Assert.Equal("data-hello", attribute.Name);
+                    Assert.Equal("world", attribute.Value);
+                });
             Assert.Equal(expectedPreContent, output.PreContent.GetContent());
             Assert.Equal(expectedContent, output.Content.GetContent());
             Assert.Equal("Content of validation summaryNew HTML", output.PostContent.GetContent());
@@ -371,8 +500,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             validationSummaryTagHelper.ViewContext = viewContext;
 
             var context = new TagHelperContext(
-                allAttributes: new TagHelperAttributeList(
+                allAttributes: new TagHelperAttributeList(),
-                    Enumerable.Empty<TagHelperAttribute>()),
                 items: new Dictionary<object, object>(),
                 uniqueId: "test");
 
@@ -427,8 +555,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             validationSummaryTagHelper.ViewContext = viewContext;
 
             var context = new TagHelperContext(
-                allAttributes: new TagHelperAttributeList(
+                allAttributes: new TagHelperAttributeList(),
-                    Enumerable.Empty<TagHelperAttribute>()),
                 items: new Dictionary<object, object>(),
                 uniqueId: "test");
 

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Rendering/HtmlHelperValidationSummaryTest.cs

@@ -75,9 +75,6 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
         {
             get
             {
-                var basicDiv = "<div class=\"HtmlEncode[[validation-summary-errors]]\"><ul>" +
-                    "<li style=\"display:none\"></li>" + Environment.NewLine +
-                    "</ul></div>";
                 var divWithError = "<div class=\"HtmlEncode[[validation-summary-errors]]\"><ul>" +
                     "<li>HtmlEncode[[This is my validation message]]</li>" + Environment.NewLine +
                     "</ul></div>";
@@ -89,8 +86,8 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
                 {
                     { false, false, divWithError, divWithError },
                     { false, true, divWithErrorAndSummary, divWithErrorAndSummary },
-                    { true, false, divWithError, basicDiv },
+                    { true, false, divWithError, string.Empty },
-                    { true, true, divWithError, basicDiv },
+                    { true, true, divWithError, string.Empty },
                 };
             }
         }
@@ -100,9 +97,6 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
         {
             get
             {
-                var basicDiv = "<div class=\"HtmlEncode[[validation-summary-errors]]\"><ul>" +
-                    "<li style=\"display:none\"></li>" + Environment.NewLine +
-                    "</ul></div>";
                 var divWithRootError = "<div class=\"HtmlEncode[[validation-summary-errors]]\"><ul>" +
                     "<li>HtmlEncode[[This is an error for the model root.]]</li>" + Environment.NewLine +
                     "<li>HtmlEncode[[This is another error for the model root.]]</li>" + Environment.NewLine +
@@ -129,7 +123,7 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
                     { false, "some.unrelated.prefix", divWithAllErrors },
                     { true, string.Empty, divWithRootError },
                     { true, "Property3", divWithProperty3Error },
-                    { true, "some.unrelated.prefix", basicDiv },
+                    { true, "some.unrelated.prefix", string.Empty },
                 };
             }
         }
@@ -526,11 +520,7 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
             var validationSummaryResult = helper.ValidationSummary(excludePropertyErrors: true);
 
             // Assert
-            Assert.Equal(
+            Assert.Equal(HtmlString.Empty, validationSummaryResult);
-                "<div class=\"HtmlEncode[[validation-summary-errors]]\"><ul><li style=\"display:none\"></li>" +
-                Environment.NewLine +
-                "</ul></div>",
-                HtmlContentUtilities.HtmlContentToString(validationSummaryResult));
         }
 
         [Fact]
@@ -576,6 +566,7 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
         {
             // Arrange
             var helper = DefaultTemplatesUtilities.GetHtmlHelper();
+            helper.ViewData.ModelState.AddModelError(string.Empty, "Error for root");
             helper.ViewData.ModelState.AddModelError("Property1", "Error for Property1");
 
             // Act
@@ -585,7 +576,7 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
             Assert.Equal(
                 "<div class=\"HtmlEncode[[validation-summary-errors]]\"><span>HtmlEncode[[Custom Message]]</span>" +
                 Environment.NewLine +
-                "<ul><li style=\"display:none\"></li>" + Environment.NewLine +
+                "<ul><li>HtmlEncode[[Error for root]]</li>" + Environment.NewLine +
                 "</ul></div>",
                 HtmlContentUtilities.HtmlContentToString(validationSummaryResult));
         }
@@ -633,6 +624,7 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
         {
             // Arrange
             var helper = DefaultTemplatesUtilities.GetHtmlHelper();
+            helper.ViewData.ModelState.AddModelError(string.Empty, "Error for root");
             helper.ViewData.ModelState.AddModelError("Property1", "Error for Property1");
 
             // Act
@@ -642,7 +634,7 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
             Assert.Equal(
                 "<div class=\"HtmlEncode[[validation-summary-errors]]\"><div>HtmlEncode[[Custom Message]]</div>" +
                 Environment.NewLine +
-                "<ul><li style=\"display:none\"></li>" + Environment.NewLine +
+                "<ul><li>HtmlEncode[[Error for root]]</li>" + Environment.NewLine +
                 "</ul></div>",
                 HtmlContentUtilities.HtmlContentToString(validationSummaryResult));
         }
@@ -652,16 +644,20 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
         {
             // Arrange
             var helper = DefaultTemplatesUtilities.GetHtmlHelper();
+            helper.ViewData.ModelState.AddModelError(string.Empty, "Error for root");
             helper.ViewData.ModelState.AddModelError("Property1", "Error for Property1");
 
             // Act
-            var validationSummaryResult = helper.ValidationSummary(excludePropertyErrors: true, message: "Custom Message", htmlAttributes: new { attr = "value" });
+            var validationSummaryResult = helper.ValidationSummary(
+                excludePropertyErrors: true,
+                message: "Custom Message",
+                htmlAttributes: new { attr = "value" });
 
             // Assert
             Assert.Equal(
                 "<div attr=\"HtmlEncode[[value]]\" class=\"HtmlEncode[[validation-summary-errors]]\"><span>HtmlEncode[[Custom Message]]</span>" +
                 Environment.NewLine +
-                "<ul><li style=\"display:none\"></li>" + Environment.NewLine +
+                "<ul><li>HtmlEncode[[Error for root]]</li>" + Environment.NewLine +
                 "</ul></div>",
                 HtmlContentUtilities.HtmlContentToString(validationSummaryResult));
         }

test/WebSites/RazorWebSite/Controllers/HtmlHelperOptionsController.cs

@@ -23,6 +23,7 @@ namespace RazorWebSite.Controllers
                 offset: TimeSpan.FromHours(0))
             };
 
+            ModelState.AddModelError(string.Empty, "A model error occurred.");
             ModelState.AddModelError("Error", "An error occurred.");
             return View(model);
         }
@@ -42,6 +43,7 @@ namespace RazorWebSite.Controllers
                 offset: TimeSpan.FromHours(0))
             };
 
+            ModelState.AddModelError(string.Empty, "A model error occurred.");
             ModelState.AddModelError("Error", "An error occurred.");
             return View(model);
         }