Fix attribute encoding for new component generation

Author: gunndabad

.github/workflows/ci.yml

@@ -5,6 +5,7 @@ on:
     branches:
     - dev
     - main
+    - v*
     tags:
     - v*
     paths-ignore:

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 2.2.1
+
+### Fixes
+
+#### Attribute encoding
+Newly-refactored tag helpers now correctly encode their attributes.
+
 ## 2.2.0
 
 Targets GOV.UK Frontend v5.2.0.

src/GovUk.Frontend.AspNetCore/TagHelpers/ErrorMessageTagHelper.cs

@@ -98,7 +98,7 @@ await output.GetChildContentAsync() :
 
             if (validationMessage != null)
             {
-                resolvedContent = new HtmlString(HtmlEncoder.Default.Encode(validationMessage));
+                resolvedContent = validationMessage.EncodeHtml();
             }
         }
 

src/GovUk.Frontend.AspNetCore/TagHelpers/Extensions.cs

@@ -0,0 +1,12 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Html;
+
+namespace GovUk.Frontend.AspNetCore.TagHelpers;
+
+internal static class Extensions
+{
+    [return: NotNullIfNotNull(nameof(value))]
+    public static IHtmlContent? EncodeHtml(this string? value) =>
+        value is not null ? new HtmlString(HtmlEncoder.Default.Encode(value)) : null;
+}