[release/8.0] [Blazor] Blazor InputRadio is broken by IHandleEvent (#53270)

Backport of #53245 to release/8.0

/cc @javiercn

# [Blazor] Blazor InputRadio is broken by IHandleEvent

Update `InputRadioContext` to get the `CurrentValue` directly from the `InputRadioGroup` rather than using a copy that needs to be updated.

## Description

Input radio groups did not update their values correctly when the component that used them implemented IHandleEvent. When the user clicked on the input radio, the value would not be updated in the UI.

Fixes #52069

## Customer Impact

Input radio elements are not correctly updated when the component that uses them implements IHandleEvent.

## Regression?

- [X] Yes
- [ ] No

7.0

## Risk

- [ ] High
- [ ] Medium
- [X] Low

[Justify the selection above]

## Verification

- [ ] Manual (required)
- [X] Automated

## Packaging changes reviewed?

- [ ] Yes
- [ ] No
- [x] N/A

----

## When servicing release/2.1

- [ ] Make necessary changes in eng/PatchConfig.props

---------

Co-authored-by: jacalvar <[email protected]>

Author: github-actions[bot]

src/Components/Web/src/Forms/IInputRadioValueProvider.cs

@@ -0,0 +1,9 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components;
+
+internal interface IInputRadioValueProvider
+{
+    public object? CurrentValue { get; }
+}

src/Components/Web/src/Forms/InputRadioContext.cs

@@ -8,21 +8,19 @@ namespace Microsoft.AspNetCore.Components.Forms;
 /// </summary>
 internal sealed class InputRadioContext
 {
+    private readonly IInputRadioValueProvider _valueProvider;
+
     public InputRadioContext? ParentContext { get; }
     public EventCallback<ChangeEventArgs> ChangeEventCallback { get; }
+    public object? CurrentValue => _valueProvider.CurrentValue;
 
     // Mutable properties that may change any time an InputRadioGroup is rendered
     public string? GroupName { get; set; }
-    public object? CurrentValue { get; set; }
     public string? FieldClass { get; set; }
 
-    /// <summary>
-    /// Instantiates a new <see cref="InputRadioContext" />.
-    /// </summary>
-    /// <param name="parentContext">The parent context, if any.</param>
-    /// <param name="changeEventCallback">The event callback to be invoked when the selected value is changed.</param>
-    public InputRadioContext(InputRadioContext? parentContext, EventCallback<ChangeEventArgs> changeEventCallback)
+    public InputRadioContext(IInputRadioValueProvider valueProvider, InputRadioContext? parentContext, EventCallback<ChangeEventArgs> changeEventCallback)
     {
+        _valueProvider = valueProvider;
         ParentContext = parentContext;
         ChangeEventCallback = changeEventCallback;
     }

src/Components/Web/src/Forms/InputRadioGroup.cs

@@ -10,7 +10,7 @@ namespace Microsoft.AspNetCore.Components.Forms;
 /// <summary>
 /// Groups child <see cref="InputRadio{TValue}"/> components.
 /// </summary>
-public class InputRadioGroup<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] TValue> : InputBase<TValue>
+public class InputRadioGroup<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] TValue> : InputBase<TValue>, IInputRadioValueProvider
 {
     private readonly string _defaultGroupName = Guid.NewGuid().ToString("N");
     private InputRadioContext? _context;
@@ -27,14 +27,16 @@ public class InputRadioGroup<[DynamicallyAccessedMembers(DynamicallyAccessedMemb
 
     [CascadingParameter] private InputRadioContext? CascadedContext { get; set; }
 
+    object? IInputRadioValueProvider.CurrentValue => CurrentValue;
+
     /// <inheritdoc />
     protected override void OnParametersSet()
     {
         // On the first render, we can instantiate the InputRadioContext
         if (_context is null)
         {
             var changeEventCallback = EventCallback.Factory.CreateBinder<string?>(this, __value => CurrentValueAsString = __value, CurrentValueAsString);
-            _context = new InputRadioContext(CascadedContext, changeEventCallback);
+            _context = new InputRadioContext(this, CascadedContext, changeEventCallback);
         }
         else if (_context.ParentContext != CascadedContext)
         {
@@ -59,7 +61,7 @@ protected override void OnParametersSet()
             // Otherwise, just use a GUID to disambiguate this group's radio inputs from any others on the page.
             _context.GroupName = _defaultGroupName;
         }
-        _context.CurrentValue = CurrentValue;
+
         _context.FieldClass = EditContext?.FieldCssClass(FieldIdentifier);
     }
 

src/Components/test/E2ETest/Tests/FormsTest.cs

@@ -844,6 +844,30 @@ public void InputRadioGroupWorksWithMutatingSetter()
         Browser.Equal("False", () => tuesday.GetDomProperty("checked"));
     }
 
+    [Theory]
+    [InlineData(0)]
+    [InlineData(2)]
+    public void InputRadioGroupWorksWithParentImplementingIHandleEvent(int n)
+    {
+        Browser.Url = new UriBuilder(Browser.Url) { Query = ($"?n={n}") }.ToString();
+        var appElement = Browser.MountTestComponent<InputRadioParentImplementsIHandleEvent>();
+        var zero = appElement.FindElement(By.Id("inputradiogroup-parent-ihandle-event-0"));
+        var one = appElement.FindElement(By.Id("inputradiogroup-parent-ihandle-event-1"));
+
+        Browser.Equal(n == 0 ? "True" : "False", () => zero.GetDomProperty("checked"));
+        Browser.Equal("False", () => one.GetDomProperty("checked"));
+
+        // Observe the changes after a click
+        one.Click();
+        Browser.Equal("False", () => zero.GetDomProperty("checked"));
+        Browser.Equal("True", () => one.GetDomProperty("checked"));
+
+        // Ensure other options can be selected
+        zero.Click();
+        Browser.Equal("False", () => one.GetDomProperty("checked"));
+        Browser.Equal("True", () => zero.GetDomProperty("checked"));
+    }
+
     [Fact]
     public void InputSelectWorksWithMutatingSetter()
     {

src/Components/test/testassets/BasicTestApp/FormsTest/InputRadioParentImplementsIHandleEvent.razor

@@ -0,0 +1,14 @@
+@using Microsoft.AspNetCore.Components.Forms
+@implements IHandleEvent
+
+<InputRadioGroup @bind-Value="N">
+  <InputRadio id="inputradiogroup-parent-ihandle-event-0" Value="0" />
+  <InputRadio id="inputradiogroup-parent-ihandle-event-1" Value="1" />
+</InputRadioGroup>
+
+@code {
+
+  [SupplyParameterFromQuery(Name = "n")] int? N { get; set; }
+
+  Task IHandleEvent.HandleEventAsync(EventCallbackWorkItem callback, object arg) => callback.InvokeAsync(arg);
+}

src/Components/test/testassets/BasicTestApp/Index.razor

@@ -49,6 +49,7 @@
         <option value="BasicTestApp.FormsTest.InputRangeComponent">Input range</option>
         <option value="BasicTestApp.FormsTest.InputsWithoutEditForm">Inputs without EditForm</option>
         <option value="BasicTestApp.FormsTest.InputsWithMutatingSetters">Inputs with mutating setters</option>
+        <option value="BasicTestApp.FormsTest.InputRadioParentImplementsIHandleEvent">Input Radio Parent Implements IHandleEvent</option>
         <option value="BasicTestApp.NavigateOnSubmit">Navigate to submit</option>
         <option value="BasicTestApp.GlobalizationBindCases">Globalization Bind Cases</option>
         <option value="BasicTestApp.GracefulTermination">Graceful Termination</option>