Fix visibility of existing documentation links in cases

LehrerApp.Desktop.Tests/StudentVorgaengeViewModelTests.cs

@@ -11,6 +11,46 @@ namespace LehrerApp.Desktop.Tests;
 /// Roster-/WebUntis-Abhängigkeit, deshalb reine In-Memory-Fakes ohne Untis-Cache-Setup.
 public sealed class StudentVorgaengeViewModelTests
 {
+    [Fact]
+    public async Task BestehenderAkteneintrag_KannNachtraeglichVerknuepftUndWiederGeloestWerden()
+    {
+        var student = new Student { FirstName = "Anna", LastName = "Beispiel" };
+        var doc = new Documentation { StudentId = student.Id, Title = "Bericht" };
+        var documentation = new FakeDocumentation();
+        documentation.Add(doc);
+        var vorgaenge = new FakeVorgangRepository();
+        var vorgang = new Vorgang { Title = "Vorgang", StudentIds = [student.Id] };
+        vorgaenge.Add(vorgang);
+        var vm = BuildVm(vorgaenge, documentation, new FakeStudents([student]));
+        vm.Load(student.Id);
+        var item = Assert.Single(vm.Cases);
+        item.IsRevealed = true;
+        var available = Assert.Single(item.AvailableDocumentation);
+        var notifications = new List<string?>();
+        item.PropertyChanged += (_, e) => notifications.Add(e.PropertyName);
+
+        // Die View bindet schon vor dem Befuellen der Collections an diese Eigenschaften.
+        item.AvailableDocumentation.Clear();
+        Assert.Contains(nameof(VorgangItem.HasAvailableDocumentation), notifications);
+        Assert.False(item.HasAvailableDocumentation);
+        item.AvailableDocumentation.Add(available);
+        Assert.True(item.HasAvailableDocumentation);
+
+        await item.LinkCommand.ExecuteAsync(available);
+        var linked = Assert.Single(vm.Cases);
+        Assert.True(linked.IsRevealed);
+        Assert.True(linked.HasLinkedDocumentation);
+        Assert.False(linked.HasAvailableDocumentation);
+        Assert.Equal(doc.Id, Assert.Single(linked.LinkedDocumentation).Model.Id);
+        Assert.Contains(doc.Id, vorgaenge.GetById(vorgang.Id)!.DocumentationIds);
+
+        await linked.UnlinkCommand.ExecuteAsync(linked.LinkedDocumentation[0]);
+        var unlinked = Assert.Single(vm.Cases);
+        Assert.False(unlinked.HasLinkedDocumentation);
+        Assert.True(unlinked.HasAvailableDocumentation);
+        Assert.Empty(vorgaenge.GetById(vorgang.Id)!.DocumentationIds);
+        Assert.Equal(doc.Id, Assert.Single(documentation.GetByStudent(student.Id)).Id);
+    }
     private static StudentVorgaengeViewModel BuildVm(FakeVorgangRepository? vorgaenge = null,
         FakeDocumentation? documentation = null, FakeStudents? students = null) =>
         new(vorgaenge ?? new FakeVorgangRepository(), documentation ?? new FakeDocumentation(),

LehrerApp.Desktop/ViewModels/ClassTeacher/VorgangViewModels.cs

@@ -90,6 +90,9 @@ public partial class VorgangItem : ObservableObject
         _onUnlink = onUnlink;
         _onRemoveClassRegisterEntry = onRemoveClassRegisterEntry;
         _onEditDocumentation = onEditDocumentation;
+        LinkedDocumentation.CollectionChanged += (_, _) => OnPropertyChanged(nameof(HasLinkedDocumentation));
+        AvailableDocumentation.CollectionChanged += (_, _) => OnPropertyChanged(nameof(HasAvailableDocumentation));
+        ClassRegisterRows.CollectionChanged += (_, _) => OnPropertyChanged(nameof(HasClassRegisterRows));
     }
 
     [RelayCommand] private void Reveal() => IsRevealed = !IsRevealed;