feat: TaskEditing_Fails_MessageNotifiesUserAndTaskRemainsUnmodified

Author: Xiphereal

Desktop.Tests/TestAPI/TaskFactory.cs

@@ -15,6 +15,16 @@ public static Task DesktopTask(string named)
         return DesktopTask(id: null, named, description: null);
     }
 
+    public static Task DesktopTask(
+        string named,
+        string description)
+    {
+        return DesktopTask(
+            id: Guid.NewGuid(),
+            named,
+            description: description);
+    }
+
     public static Task DesktopTask(
         Guid? id = null,
         string named = null,

Desktop.Tests/UnitTests/TaskEditingViewModelTests.cs

@@ -1,5 +1,8 @@
-using Desktop.Domain;
+using Desktop.Common;
+using Desktop.Domain;
 using Desktop.Tasks;
+using Desktop.Tests.TestAPI;
+using FluentAssertions;
 using Moq;
 using NUnit.Framework;
 using static Desktop.Tests.TestAPI.TaskFactory;
@@ -11,15 +14,58 @@ public class TaskEditingViewModelTests
     [Test]
     public void TasksModificationsAreCommandedToBePersisted()
     {
-        var aRepositoryMock = new Mock<ITaskRepository>();
-        var anotherRepositoryMock = new Mock<ITaskRepository>();
+        var aRepositoryMock = RepositoryMockThatAlwaysSucceeds();
+        var anotherRepositoryMock = RepositoryMockThatAlwaysSucceeds();
+        var sut = TaskEditingViewModel(
+            taskBeingEdited: AnyDesktopTask(),
+            repositories: [aRepositoryMock.Object, anotherRepositoryMock.Object]);
 
-        var sut = new TaskEditingViewModel(
-            AnyDesktopTask(),
-            [aRepositoryMock.Object, anotherRepositoryMock.Object]);
         sut.Save.Execute(("New name", "New description"));
 
         aRepositoryMock.Verify(m => m.Save(It.IsAny<Task>()));
         anotherRepositoryMock.Verify(m => m.Save(It.IsAny<Task>()));
     }
+
+    private static Mock<ITaskRepository> RepositoryMockThatAlwaysSucceeds()
+    {
+        var mock = new Mock<ITaskRepository>();
+        mock
+            .Setup(x => x.Save(It.IsAny<Task>()))
+            .ReturnsAsync(ResultWithoutValue.Success());
+
+        return mock;
+    }
+
+    [Test]
+    public void TaskEditing_Fails_MessageNotifiesUserAndTaskRemainsUnmodified()
+    {
+        var existingTask = DesktopTask("Old name", "Old description");
+        var repository = new InMemoryTaskRepository([existingTask]);
+        repository.FailAlways();
+        var messageNotifierMock = new Mock<IMessageNotifier>();
+        var sut = TaskEditingViewModel(
+            taskBeingEdited: existingTask,
+            messageNotifierMock.Object,
+            repositories: repository);
+
+        sut.Save.Execute(("New name", "New description"));
+
+        messageNotifierMock.Verify(x => x.Notify(
+            "Task editing has failed due to " +
+            "an internal error. The modifications will be reverted. " +
+            "Please, try again later."));
+        existingTask.Name.Should().Be("Old name");
+        existingTask.Description.Should().Be("Old description");
+    }
+
+    private static TaskEditingViewModel TaskEditingViewModel(
+        Task taskBeingEdited,
+        IMessageNotifier messageNotifier = null,
+        params ITaskRepository[] repositories)
+    {
+        return new TaskEditingViewModel(
+            taskBeingEdited,
+            messageNotifier ?? new Mock<IMessageNotifier>().Object,
+            repositories);
+    }
 }

Desktop/MainWindow.xaml.cs

@@ -1,4 +1,5 @@
 using System.Windows;
+using Desktop.Common;
 using Desktop.Project;
 using Desktop.Tasks;
 
@@ -7,14 +8,17 @@ namespace Desktop;
 public partial class MainWindow : Window
 {
     private readonly TaskListViewModel taskListViewModel;
+    private readonly IMessageNotifier messageNotifier;
     private readonly IEnumerable<ITaskRepository> taskRepositories;
 
     public MainWindow(
         TaskListViewModel taskListViewModel,
         MainWindowViewModel viewModel,
+        IMessageNotifier messageNotifier,
         IEnumerable<ITaskRepository> taskRepositories)
     {
         this.taskListViewModel = taskListViewModel;
+        this.messageNotifier = messageNotifier;
         this.taskRepositories = taskRepositories;
         DataContext = viewModel;
 
@@ -24,7 +28,7 @@ public MainWindow(
 
     private void NavigateToTaskList()
     {
-        var tasksList = new TasksList(taskListViewModel, taskRepositories);
+        var tasksList = new TasksList(taskListViewModel, messageNotifier, taskRepositories);
         Content.Content = tasksList;
     }
 

Desktop/Project/TasksList.xaml.cs

@@ -1,18 +1,22 @@
 using System.Windows.Controls;
 using System.Windows.Input;
+using Desktop.Common;
 using Desktop.Tasks;
 using Task = Desktop.Domain.Task;
 
 namespace Desktop.Project;
 
 public partial class TasksList : UserControl
 {
+    private readonly IMessageNotifier messageNotifier;
     private readonly IEnumerable<ITaskRepository> taskRepositories;
 
     public TasksList(
         TaskListViewModel viewModel,
+        IMessageNotifier messageNotifier,
         IEnumerable<ITaskRepository> taskRepositories)
     {
+        this.messageNotifier = messageNotifier;
         this.taskRepositories = taskRepositories;
         DataContext = viewModel;
 
@@ -37,7 +41,7 @@ private void Edit(object sender, MouseButtonEventArgs e)
         if (sender is not ListBoxItem { DataContext: Task task })
             return;
 
-        var window = new TaskEditing(task, taskRepositories);
+        var window = new TaskEditing(task, messageNotifier, taskRepositories);
         window.ShowDialog();
     }
 }

Desktop/Tasks/TaskEditing.xaml.cs

@@ -1,4 +1,5 @@
 using System.Windows;
+using Desktop.Common;
 using Task = Desktop.Domain.Task;
 
 namespace Desktop.Tasks;
@@ -9,11 +10,14 @@ public partial class TaskEditing : Window
 {
     private readonly TaskEditingViewModel viewModel;
 
-    public TaskEditing(Task original, IEnumerable<ITaskRepository> taskRepositories)
+    public TaskEditing(
+        Task original,
+        IMessageNotifier messageNotifier,
+        IEnumerable<ITaskRepository> taskRepositories)
     {
         InitializeComponent();
 
-        viewModel = new TaskEditingViewModel(original, taskRepositories);
+        viewModel = new TaskEditingViewModel(original, messageNotifier, taskRepositories);
 
         Name.Text = original.Name;
         Description.Text = original.Description;

Desktop/Tasks/TaskEditingViewModel.cs

@@ -9,17 +9,33 @@ public class TaskEditingViewModel : ViewModelBase
 {
     public TaskEditingViewModel(
         Task taskBeingEdited,
+        IMessageNotifier messageNotifier,
         IEnumerable<ITaskRepository> taskRepositories)
     {
         Save = new AsyncRelayCommand<(string, string)>(async args =>
         {
             var (name, description) = args;
 
+            var originalName = taskBeingEdited.Name;
             taskBeingEdited.Name = name;
+            var originalDescription = taskBeingEdited.Description;
             taskBeingEdited.Description = description;
 
             foreach (var repository in taskRepositories)
-                await repository.Save(taskBeingEdited);
+            {
+                var editingResult = await repository.Save(taskBeingEdited);
+
+                if (!editingResult.Succeeded)
+                {
+                    messageNotifier.Notify(
+                        "Task editing has failed due to " +
+                        "an internal error. The modifications will be reverted. " +
+                        "Please, try again later.");
+
+                    taskBeingEdited.Name = originalName;
+                    taskBeingEdited.Description = originalDescription;
+                }
+            }
         });
     }