Add a System.Text.Json based IJsonHelper (#9566)

* Add a System.Text.Json based IJsonHelper

Fixes https://github.com/aspnet/AspNetCore/issues/9564

src/Mvc/Mvc.NewtonsoftJson/test/DependencyInjection/NewtonsoftJsonMvcCoreBuilderExtensionsTest.cs

@@ -36,7 +36,7 @@ namespace Microsoft.Extensions.DependencyInjection
         {
             // Arrange
             var services = new ServiceCollection()
-                .AddSingleton<IJsonHelper, DefaultJsonHelper>();
+                .AddSingleton<IJsonHelper, SystemTextJsonHelper>();
 
             // Act
             NewtonsoftJsonMvcCoreBuilderExtensions.AddServicesCore(services);

src/Mvc/Mvc.NewtonsoftJson/test/Microsoft.AspNetCore.Mvc.NewtonsoftJson.Test.csproj

@@ -16,6 +16,7 @@
     <Compile Include="..\..\Mvc.Core\test\Formatters\JsonOutputFormatterTestBase.cs" />
     <Compile Include="..\..\Mvc.Core\test\Infrastructure\JsonResultExecutorTestBase.cs" />
     <Compile Include="..\..\Mvc.ViewFeatures\test\Infrastructure\TempDataSerializerTestBase.cs" />
+    <Compile Include="..\..\Mvc.ViewFeatures\test\Rendering\JsonHelperTestBase.cs" />
   </ItemGroup>
 
 </Project>

src/Mvc/Mvc.NewtonsoftJson/test/NewtonsoftJsonHelperTest.cs

@@ -3,6 +3,7 @@
 
 using System.Buffers;
 using Microsoft.AspNetCore.Html;
+using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.Extensions.Options;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
@@ -10,31 +11,8 @@ using Xunit;
 
 namespace Microsoft.AspNetCore.Mvc.NewtonsoftJson
 {
-    public class NewtonsoftJsonHelperTest
+    public class NewtonsoftJsonHelperTest : JsonHelperTestBase
     {
-        [Fact]
-        public void Serialize_EscapesHtmlByDefault()
-        {
-            // Arrange
-            var options = new MvcNewtonsoftJsonOptions();
-            options.SerializerSettings.StringEscapeHandling = StringEscapeHandling.EscapeNonAscii;
-            var helper = new NewtonsoftJsonHelper(
-                Options.Create(options),
-                ArrayPool<char>.Shared);
-            var obj = new
-            {
-                HTML = "<b>John Doe</b>"
-            };
-            var expectedOutput = "{\"html\":\"\\u003cb\\u003eJohn Doe\\u003c/b\\u003e\"}";
-
-            // Act
-            var result = helper.Serialize(obj);
-
-            // Assert
-            var htmlString = Assert.IsType<HtmlString>(result);
-            Assert.Equal(expectedOutput, htmlString.ToString());
-        }
-
         [Fact]
         public void Serialize_MaintainsSettingsAndEscapesHtml()
         {
@@ -65,10 +43,7 @@ namespace Microsoft.AspNetCore.Mvc.NewtonsoftJson
         public void Serialize_UsesHtmlSafeVersionOfPassedInSettings()
         {
             // Arrange
-            var options = new MvcNewtonsoftJsonOptions();
+            var helper = GetJsonHelper();
-            var helper = new NewtonsoftJsonHelper(
-                Options.Create(options),
-                ArrayPool<char>.Shared);
             var obj = new
             {
                 FullHtml = "<b>John Doe</b>"
@@ -91,5 +66,33 @@ namespace Microsoft.AspNetCore.Mvc.NewtonsoftJson
             var htmlString = Assert.IsType<HtmlString>(result);
             Assert.Equal(expectedOutput, htmlString.ToString());
         }
+
+        [Fact]
+        public override void Serialize_WithNonAsciiChars()
+        {
+            // Arrange
+            var helper = GetJsonHelper();
+            var obj = new
+            {
+                HTML = $"Hello pingüino"
+            };
+            var expectedOutput = $"{{\"html\":\"{obj.HTML}\"}}";
+
+            // Act
+            var result = helper.Serialize(obj);
+
+            // Assert
+            var htmlString = Assert.IsType<HtmlString>(result);
+            Assert.Equal(expectedOutput, htmlString.ToString());
+        }
+
+        protected override IJsonHelper GetJsonHelper()
+        {
+            var options = new MvcNewtonsoftJsonOptions();
+            var helper = new NewtonsoftJsonHelper(
+                Options.Create(options),
+                ArrayPool<char>.Shared);
+            return helper;
+        }
     }
 }

src/Mvc/Mvc.ViewFeatures/src/DependencyInjection/MvcViewFeaturesMvcCoreBuilderExtensions.cs

@@ -172,7 +172,7 @@ namespace Microsoft.Extensions.DependencyInjection
             services.TryAddSingleton<IModelExpressionProvider>(s => s.GetRequiredService<ModelExpressionProvider>());
             services.TryAddSingleton<ValidationHtmlAttributeProvider, DefaultValidationHtmlAttributeProvider>();
 
-            services.TryAddSingleton<IJsonHelper, DefaultJsonHelper>();
+            services.TryAddSingleton<IJsonHelper, SystemTextJsonHelper>();
 
             //
             // View Components

src/Mvc/Mvc.ViewFeatures/src/Rendering/DefaultJsonHelper.cs

@@ -1,24 +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 Microsoft.AspNetCore.Html;
-using Microsoft.Extensions.DependencyInjection;
-
-namespace Microsoft.AspNetCore.Mvc.Rendering
-{
-    internal class DefaultJsonHelper : IJsonHelper
-    {
-        /// <inheritdoc />
-        public IHtmlContent Serialize(object value)
-        {
-            throw new InvalidOperationException(Core.Resources.FormatReferenceToNewtonsoftJsonRequired(
-               $"{nameof(IJsonHelper)}.{nameof(Serialize)}",
-               "Microsoft.AspNetCore.Mvc.NewtonsoftJson",
-               nameof(IMvcBuilder),
-               "AddNewtonsoftJson",
-               "ConfigureServices(...)"));
-        }
-    }
-}

src/Mvc/Mvc.ViewFeatures/src/Rendering/SystemTextJsonHelper.cs

@@ -0,0 +1,29 @@
+
+// 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.Text.Json.Serialization;
+using Microsoft.AspNetCore.Html;
+using Microsoft.Extensions.Options;
+
+namespace Microsoft.AspNetCore.Mvc.Rendering
+{
+    internal class SystemTextJsonHelper : IJsonHelper
+    {
+        private readonly MvcOptions _mvcOptions;
+
+        public SystemTextJsonHelper(IOptions<MvcOptions> mvcOptions)
+        {
+            _mvcOptions = mvcOptions.Value;
+        }
+
+        /// <inheritdoc />
+        public IHtmlContent Serialize(object value)
+        {
+            // JsonSerializer always encodes non-ASCII chars, so we do not need
+            // to do anything special with the SerializerOptions
+            var json = JsonSerializer.ToString(value, _mvcOptions.SerializerOptions);
+            return new HtmlString(json);
+        }
+    }
+}

src/Mvc/Mvc.ViewFeatures/test/Rendering/JsonHelperTestBase.cs

@@ -0,0 +1,103 @@
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNetCore.Html;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.Rendering
+{
+    public abstract class JsonHelperTestBase
+    {
+        protected abstract IJsonHelper GetJsonHelper();
+
+        [Fact]
+        public void Serialize_EscapesHtmlByDefault()
+        {
+            // Arrange
+            var helper = GetJsonHelper();
+            var obj = new
+            {
+                HTML = "<b>John Doe</b>"
+            };
+            var expectedOutput = "{\"html\":\"\\u003cb\\u003eJohn Doe\\u003c/b\\u003e\"}";
+
+            // Act
+            var result = helper.Serialize(obj);
+
+            // Assert
+            var htmlString = Assert.IsType<HtmlString>(result);
+            Assert.Equal(expectedOutput, htmlString.ToString());
+        }
+
+        [Fact]
+        public void Serialize_WithNullValue()
+        {
+            // Arrange
+            var helper = GetJsonHelper();
+            var expectedOutput = "null";
+
+            // Act
+            var result = helper.Serialize(value: null);
+
+            // Assert
+            var htmlString = Assert.IsType<HtmlString>(result);
+            Assert.Equal(expectedOutput, htmlString.ToString());
+        }
+
+        [Fact]
+        public void Serialize_WithControlCharacters()
+        {
+            // Arrange
+            var helper = GetJsonHelper();
+            var obj = new
+            {
+                HTML = $"Hello \n \b \a world"
+            };
+            var expectedOutput = "{\"html\":\"Hello \\n \\b \\u0007 world\"}";
+
+            // Act
+            var result = helper.Serialize(obj);
+
+            // Assert
+            var htmlString = Assert.IsType<HtmlString>(result);
+            Assert.Equal(expectedOutput, htmlString.ToString());
+        }
+
+        [Fact]
+        public virtual void Serialize_WithNonAsciiChars()
+        {
+            // Arrange
+            var helper = GetJsonHelper();
+            var obj = new
+            {
+                HTML = $"Hello pingüino"
+            };
+            var expectedOutput = "{\"html\":\"Hello ping\\u00fcino\"}";
+
+            // Act
+            var result = helper.Serialize(obj);
+
+            // Assert
+            var htmlString = Assert.IsType<HtmlString>(result);
+            Assert.Equal(expectedOutput, htmlString.ToString());
+        }
+
+        [Fact]
+        public void Serialize_WithHTMLEntities()
+        {
+            // Arrange
+            var helper = GetJsonHelper();
+            var obj = new
+            {
+                HTML = $"Hello &nbsp; &lt;John&gt;"
+            };
+            var expectedOutput = "{\"html\":\"Hello \\u0026nbsp; \\u0026lt;John\\u0026gt;\"}";
+
+            // Act
+            var result = helper.Serialize(obj);
+
+            // Assert
+            var htmlString = Assert.IsType<HtmlString>(result);
+            Assert.Equal(expectedOutput, htmlString.ToString());
+        }
+    }
+}

src/Mvc/Mvc.ViewFeatures/test/Rendering/SystemTextJsonHelperTest.cs

@@ -0,0 +1,19 @@
+
+// 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.Text.Json.Serialization;
+using Microsoft.Extensions.Options;
+
+namespace Microsoft.AspNetCore.Mvc.Rendering
+{
+    public class SystemTextJsonHelperTest : JsonHelperTestBase
+    {
+        protected override IJsonHelper GetJsonHelper()
+        {
+            var mvcOptions = new MvcOptions { SerializerOptions = { PropertyNamingPolicy = JsonNamingPolicy.CamelCase } };
+            return new SystemTextJsonHelper(Options.Create(mvcOptions));
+        }
+    }
+}