Fix nested list selection state in MudSelectExtended

src/CodeBeam.MudBlazor.Extensions/Components/ListExtended/MudListExtended.razor.cs

@@ -513,7 +513,7 @@ protected internal void UpdateSelectedValue()
         [Category(CategoryTypes.List.Selecting)]
         public T? SelectedValue
         {
-            get => _selectedValue;
+            get => ParentList != null ? ParentList.SelectedValue : _selectedValue;
             set
             {
                 if (Converter.Convert(_selectedValue) != Converter.Convert(default(T)) && !_firstRendered)
@@ -549,7 +549,7 @@ public IEnumerable<T?>? SelectedValues
         {
             get
             {
-                return _selectedValues;
+                return ParentList != null ? ParentList.SelectedValues : _selectedValues;
             }
 
             set

tests/CodeBeam.MudBlazor.Extensions.UnitTests.Viewer/TestComponents/SelectExtended/SelectNestedMultiSelectionTest.razor

@@ -0,0 +1,37 @@
+@namespace MudExtensions.UnitTests.TestComponents
+
+<MudPopoverProvider />
+
+<MudSelectExtended T="string" MultiSelection="true" Clearable="true"
+                   SelectedValues="SelectedValues" SelectedValuesChanged="OnSelectedValuesChanged">
+    <MudSelectItemGroupExtended T="string" Text="Station A" Nested="true" InitiallyExpanded="InitiallyExpanded">
+        <MudSelectItemExtended T="string" Value="@("electric")" Text="Electricity" />
+        <MudSelectItemExtended T="string" Value="@("flow")" Text="Flow" />
+        <MudSelectItemExtended T="string" Value="@("pressure")" Text="Pressure" />
+    </MudSelectItemGroupExtended>
+    <MudSelectItemGroupExtended T="string" Text="Station B" Nested="true" InitiallyExpanded="InitiallyExpanded">
+        <MudSelectItemExtended T="string" Value="@("temperature")" Text="Temperature" />
+    </MudSelectItemGroupExtended>
+</MudSelectExtended>
+
+@code {
+    [Parameter]
+    public bool InitiallyExpanded { get; set; } = true;
+
+    public IEnumerable<string> SelectedValues { get; private set; } = ["electric"];
+
+    public List<string[]> SelectionChanges { get; } = new();
+
+    public void SetSelectedValues(params string[] values)
+    {
+        SelectedValues = values;
+        StateHasChanged();
+    }
+
+    private void OnSelectedValuesChanged(IEnumerable<string>? values)
+    {
+        var snapshot = values?.ToArray() ?? [];
+        SelectedValues = snapshot;
+        SelectionChanges.Add(snapshot);
+    }
+}

tests/CodeBeam.MudBlazor.Extensions.UnitTests/Components/SelectExtendedNestedSelectionTests.cs

@@ -0,0 +1,116 @@
+using AwesomeAssertions;
+using Bunit;
+using MudExtensions.UnitTests.TestComponents;
+
+namespace MudExtensions.UnitTests.Components
+{
+    [TestFixture]
+    public class SelectExtendedNestedSelectionTests : BunitTest
+    {
+        [TestCase(false)]
+        [TestCase(true)]
+        public void NestedMultiSelection_SelectingItem_PreservesExistingSelection(bool initiallyExpanded)
+        {
+            var cut = Context.Render<SelectNestedMultiSelectionTest>(parameters => parameters
+                .Add(x => x.InitiallyExpanded, initiallyExpanded));
+
+            cut.Find("div.mud-input-control").Click();
+            if (!initiallyExpanded)
+                cut.Find("[role='option'][aria-label='Station A']").Click();
+
+            var callbacks = cut.Instance.SelectionChanges.Count;
+            cut.Find("[role='option'][aria-label='Pressure']").Click();
+
+            cut.WaitForAssertion(() =>
+            {
+                cut.Instance.SelectedValues.Should().BeEquivalentTo(new[] { "electric", "pressure" });
+                cut.Instance.SelectionChanges.Should().HaveCount(callbacks + 1);
+                cut.Find("[role='option'][aria-label='Electricity']").GetAttribute("aria-selected").Should().Be("true");
+                cut.Find("[role='option'][aria-label='Pressure']").GetAttribute("aria-selected").Should().Be("true");
+            });
+        }
+
+        [Test]
+        public async Task NestedMultiSelection_ParentUpdates_ArePreservedWhenSelectingInAnotherGroup()
+        {
+            var cut = Context.Render<SelectNestedMultiSelectionTest>();
+            cut.Find("div.mud-input-control").Click();
+
+            await cut.InvokeAsync(() => cut.Instance.SetSelectedValues("flow", "pressure"));
+            var callbacks = cut.Instance.SelectionChanges.Count;
+            cut.Find("[role='option'][aria-label='Temperature']").Click();
+
+            cut.WaitForAssertion(() =>
+            {
+                cut.Instance.SelectedValues.Should().BeEquivalentTo(new[] { "flow", "pressure", "temperature" });
+                cut.Instance.SelectionChanges.Should().HaveCount(callbacks + 1);
+                cut.Find("[role='option'][aria-label='Electricity']").GetAttribute("aria-selected").Should().Be("false");
+                cut.Find("[role='option'][aria-label='Flow']").GetAttribute("aria-selected").Should().Be("true");
+                cut.Find("[role='option'][aria-label='Pressure']").GetAttribute("aria-selected").Should().Be("true");
+                cut.Find("[role='option'][aria-label='Temperature']").GetAttribute("aria-selected").Should().Be("true");
+            });
+        }
+
+        [Test]
+        public async Task NestedMultiSelection_DeselectingItem_PreservesOtherSelections()
+        {
+            var cut = Context.Render<SelectNestedMultiSelectionTest>();
+            cut.Find("div.mud-input-control").Click();
+
+            await cut.InvokeAsync(() => cut.Instance.SetSelectedValues("electric", "pressure", "temperature"));
+            var callbacks = cut.Instance.SelectionChanges.Count;
+            cut.Find("[role='option'][aria-label='Pressure']").Click();
+
+            cut.WaitForAssertion(() =>
+            {
+                cut.Instance.SelectedValues.Should().BeEquivalentTo(new[] { "electric", "temperature" });
+                cut.Instance.SelectionChanges.Should().HaveCount(callbacks + 1);
+                cut.Find("[role='option'][aria-label='Pressure']").GetAttribute("aria-selected").Should().Be("false");
+                cut.Find("[role='option'][aria-label='Temperature']").GetAttribute("aria-selected").Should().Be("true");
+            });
+        }
+
+        [Test]
+        public void NestedMultiSelection_ClickingSelectedItemAgain_DeselectsItOnce()
+        {
+            var cut = Context.Render<SelectNestedMultiSelectionTest>();
+            cut.Find("div.mud-input-control").Click();
+            cut.Find("[role='option'][aria-label='Pressure']").Click();
+            var callbacks = cut.Instance.SelectionChanges.Count;
+
+            cut.Find("[role='option'][aria-label='Pressure']").Click();
+
+            cut.WaitForAssertion(() =>
+            {
+                cut.Instance.SelectedValues.Should().BeEquivalentTo(new[] { "electric" });
+                cut.Instance.SelectionChanges.Should().HaveCount(callbacks + 1);
+                cut.Find("[role='option'][aria-label='Pressure']").GetAttribute("aria-selected").Should().Be("false");
+            });
+        }
+
+        [Test]
+        public async Task NestedSingleSelection_ChildListsReadRootValueAfterChangesAndClear()
+        {
+            var cut = Context.Render<ListExperimentalSelectionInitialValueTest>();
+            var root = cut.FindComponent<MudListExtended<int?>>();
+            var lists = cut.FindComponents<MudListExtended<int?>>();
+            lists.Should().HaveCount(3);
+
+            await cut.InvokeAsync(() => cut.Instance.SetSelectedValue(4));
+            cut.WaitForAssertion(() =>
+            {
+                root.Instance.SelectedValue.Should().Be(4);
+                foreach (var list in lists)
+                    list.Instance.SelectedValue.Should().Be(4);
+            });
+
+            await cut.InvokeAsync(() => cut.Instance.SetSelectedValue(null));
+            cut.WaitForAssertion(() =>
+            {
+                root.Instance.SelectedValue.Should().BeNull();
+                foreach (var list in lists)
+                    list.Instance.SelectedValue.Should().BeNull();
+            });
+        }
+    }
+}