feat: Tasks are not removed from Task list if its deletion fails

Author: Xiphereal

Desktop.Tests/UnitTests/TaskListViewModelTests.cs

@@ -63,21 +63,28 @@ public void TaskPopulation_Fails_MessageNotifiesUser()
     }
 
     [Test]
-    public void TaskDeletion_Fails_MessageNotifiesUser()
+    public void TaskDeletion_Fails_MessageNotifiesUserAndTaskRemains()
     {
+        // Arrange.
         var existingTask = DesktopTask();
         var backendRepository =
             new InMemoryTaskRepository([existingTask]);
-        backendRepository.FailAlways();
+        
         var messageNotifierMock = new Mock<IMessageNotifier>();
+        
         var sut = TaskListViewModel(backendRepository, messageNotifierMock.Object);
-
+        sut.PopulateTasks();
+        backendRepository.FailAlways();
+        
+        // Act.
         sut.Delete.Execute(existingTask);
 
+        // Assert.
         messageNotifierMock.Verify(x => x.Notify(
             "Task deletion has failed due to " +
             "an internal error. The Task won't be deleted. " +
             "Please, try again later."));
+        sut.Tasks.Should().Contain(existingTask);
     }
 
     private static TaskListViewModel TaskListViewModel(

Desktop/Project/TaskListViewModel.cs

@@ -36,13 +36,13 @@ public TaskListViewModel(
 
         Delete = new AsyncRelayCommand<Task>(async taskToRemove =>
         {
-            Tasks.Remove(taskToRemove!);
-
             foreach (var repository in this.taskRepositories)
             {
-                var result = await repository.Delete(taskToRemove!);
+                var deletion = await repository.Delete(taskToRemove!);
 
-                if (!result.Succeeded)
+                if (deletion.Succeeded)
+                    Tasks.Remove(taskToRemove!);
+                else
                     messageNotifier.Notify(
                         "Task deletion has failed due to " +
                         "an internal error. The Task won't be deleted. " +