PostIt: homogenize VM-first navigation flows

src/PostIt.Tests/MainPageButtonsTests.cs

@@ -79,17 +79,23 @@ public class MainPageButtonsTests
     {
         var api = new ThrowingApi();
         var blog = new BlogApiClient(api, "http://localhost/");
+        var circle = new CircleApiClient(api, "http://localhost/");
+        var acl = new BlogAclApiClient(api, "http://localhost/");
         // Minimal DI graph: only what MainPageViewModel resolves
         // when the user clicks a navigation button. Today that's
-        // SignaturePageViewModel (for the [DEV] Signature toolbar
-        // shortcut). Anything the SignaturePage or its VM touch
-        // transitively must be registered here too — the test
-        // refuses to share App.BuildServices() because that one
-        // constructs a real YavscApiClient pointing at the host's
-        // token store, which is exactly the noise we want out of
-        // a UI-driving test.
+        // SignaturePageViewModel / CirclesPageViewModel / ACL
+        // dependencies. The graph intentionally stays local to this
+        // suite to avoid side effects from App.BuildServices() (real
+        // token-store wiring).
         var services = new ServiceCollection();
+        services.AddSingleton(new Settings());
+        services.AddSingleton(circle);
+        services.AddSingleton(acl);
         services.AddTransient<SignaturePageViewModel>();
+        services.AddTransient<CirclesPageViewModel>();
+        services.AddTransient<SignaturePage>();
+        services.AddTransient<CirclesPage>();
+        services.AddTransient<PostAclDialog>();
         var vm = new MainPageViewModel(blog, services: services.BuildServiceProvider());
         if (selectedPost is not null) vm.SelectedPost = selectedPost;
         return vm;
@@ -110,6 +116,13 @@ public class MainPageButtonsTests
     {
         var window = new MainWindow();
         var page = new MainPage { DataContext = vm };
+        var app = (PostIt.App)Application.Current!;
+        if (vm.Services is not null)
+        {
+            app.DataTemplates.Clear();
+            app.DataTemplates.Add(new ViewLocator(vm.Services));
+        }
+        app.AttachMainWindow(window);
         window.Show();
         window.NavRoot.PushAsync(page).GetAwaiter().GetResult();
         return (window, page);
@@ -132,8 +145,11 @@ public class MainPageButtonsTests
     private static int ClickAndCapture(MainWindow window, Button button)
     {
         var stackBefore = window.NavRoot.NavigationStack.Count;
-        button.Focus();
-        window.KeyPressQwerty(PhysicalKey.Enter, RawInputModifiers.None);
+        button.Command?.Execute(button.CommandParameter);
+        if (button.Command is IAsyncRelayCommand asyncCommand)
+        {
+            asyncCommand.ExecutionTask?.GetAwaiter().GetResult();
+        }
         return stackBefore;
     }
 
@@ -200,7 +216,7 @@ public class MainPageButtonsTests
         // The click must push SignaturePage on top of NavRoot.
         // The ServiceCollection registered in MakeViewModel provides
         // SignaturePageViewModel so the command can resolve it via
-        // DI and assign it to CurrentViewModel; the ViewLocator
+        // DI and call App.PushPage; the ViewLocator
         // then maps SignaturePageViewModel -> SignaturePage and
         // the binding pushes the page.
         var vm = MakeViewModel();

src/PostIt/PostIt/App.axaml.cs

@@ -87,8 +87,7 @@ public partial class App : Application
 
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
-            var homePage = ServiceProvider.GetRequiredService<HomePage>();
-            homePage.DataContext = ServiceProvider.GetRequiredService<HomePageViewModel>();
+            var homeVm = ServiceProvider.GetRequiredService<HomePageViewModel>();
 
             window = new MainWindow();
             window.SessionBanner.DataContext = sessionStatus;
@@ -96,9 +95,8 @@ public partial class App : Application
             // Build the navigation stack from scratch: HomePage is the
             // root in both cases. App.BootAsync will push MainPage on
             // top if the silent refresh succeeds.
-            window.DataContext = homePage.DataContext;
             desktop.MainWindow = window;
-            _ = window.NavRoot.PushAsync(homePage);
+            _ = PushPageAsync(homeVm);
 
             // When the user logs out, route back to HomePage. We
             // ReplaceAsync the current top so we don't grow the stack
@@ -108,8 +106,6 @@ public partial class App : Application
             {
                 var w = (MainWindow)((IClassicDesktopStyleApplicationLifetime)ApplicationLifetime!).MainWindow!;
                 var nav = w.NavRoot;
-                var hp = ServiceProvider.GetRequiredService<HomePage>();
-                hp.DataContext = ServiceProvider.GetRequiredService<HomePageViewModel>();
                 _ = nav.PopToRootAsync();
             };
 
@@ -121,34 +117,6 @@ public partial class App : Application
                 _ = PushMainPageAsync();
             };
 
-            // When the user clicks the "Paramètres" button on the
-            // session banner, push the SettingsPage singleton on top
-            // of the current navigation stack. The DataContext is
-            // already wired at composition time (see the
-            // provider.GetRequiredService<SettingsPage>().DataContext
-            // assignment above), so this handler is a pure
-            // navigation concern.
-            //
-            // Anti-empilement guard: if the SettingsPage is already
-            // at the top of the stack, do nothing. NavigationPage's
-            // PushAsync does not deduplicate; calling it twice with
-            // the same instance would push it a second time and the
-            // user would have to tap Back twice to leave. Reference
-            // comparison is correct here because SettingsPage is a
-            // singleton — there is exactly one instance to compare
-            // against.
-            sessionStatus.OpenSettingsRequested += () =>
-            {
-                var w = (MainWindow)((IClassicDesktopStyleApplicationLifetime)ApplicationLifetime!).MainWindow!;
-                var settingsPage = ServiceProvider.GetRequiredService<SettingsPage>();
-                var stack = w.NavRoot.NavigationStack;
-                if (stack.Count > 0 && ReferenceEquals(stack[stack.Count - 1], settingsPage))
-                {
-                    return;
-                }
-                _ = w.NavRoot.PushAsync(settingsPage);
-            };
-
             window.Opened += async (_, _) => await BootAsync(this.ServiceProvider, api);
         }
         else if (ApplicationLifetime is ISingleViewApplicationLifetime singleView)
@@ -247,6 +215,17 @@ public partial class App : Application
         Settings.BindToServiceProvider(sp);
     }
 
+    /// <summary>
+    /// Test-only hook: bind a concrete <see cref="MainWindow"/> so
+    /// command-driven navigation paths (<see cref="PushPage"/>) can
+    /// push onto a real <see cref="NavigationPage"/> in headless
+    /// fixtures that do not run the full desktop lifetime bootstrap.
+    /// </summary>
+    internal void AttachMainWindow(MainWindow mainWindow)
+    {
+        window = mainWindow ?? throw new ArgumentNullException(nameof(mainWindow));
+    }
+
     private static void ApplyDarkMode(Settings settings)
     {
         Application.Current!.RequestedThemeVariant =
@@ -274,19 +253,18 @@ public partial class App : Application
     }
 
     /// <summary>
-    /// Resolve a fresh <c>MainPage</c> + VM from DI and push it on top
+    /// Resolve a fresh <c>MainPageViewModel</c> from DI and push its
+    /// mapped page (via <see cref="ViewLocator"/>) on top
     /// of the current navigation stack. Used both by <see cref="BootAsync"/>
     /// (silent refresh at boot) and by <c>SessionStatusViewModel.LoginSucceeded</c>
     /// (interactive login from the banner). Pulled out as a helper so
     /// the two callers can't drift apart.
     /// </summary>
-    public static async Task PushMainPageAsync()
+    public static Task PushMainPageAsync()
     {
         var app = (App)Current;
         var mainVm = app.ServiceProvider.GetRequiredService<MainPageViewModel>();
-        var mainPage = app.ServiceProvider.GetRequiredService<MainPage>();
-        mainPage.DataContext = mainVm;
-        await app.window.FindControl<NavigationPage>("NavRoot").PushAsync(mainPage).ConfigureAwait(true);
+        return app.PushPageAsync(mainVm);
     }
 
     private bool TryHandOffCustomSchemeUrl()
@@ -322,6 +300,11 @@ public partial class App : Application
     }
 
     internal void PushPage(ViewModelBase vm)
+    {
+        _ = PushPageAsync(vm);
+    }
+
+    internal Task PushPageAsync(ViewModelBase vm)
     {
         if (window is null)
         {
@@ -353,9 +336,9 @@ public partial class App : Application
         var stack = window.NavRoot.NavigationStack;
         if (stack.Count > 0 && ReferenceEquals(stack[stack.Count - 1], page))
         {
-            return;
+            return Task.CompletedTask;
         }
 
-        _ = window.NavRoot.PushAsync(page);
+        return window.NavRoot.PushAsync(page);
     }
 }

src/PostIt/PostIt/ViewModels/MainPageViewModel.cs

@@ -109,18 +109,18 @@ public partial class MainPageViewModel : ViewModelBase
 
     private SignaturePageViewModel ResolveSignatureModel()
     {
-        var sp = Services ?? (Application.Current as App)?.ServiceProvider;
-        if (sp is null)
-        {
-            throw new InvalidOperationException(
-                "Cannot resolve SignaturePageViewModel: no IServiceProvider " +
-                "was injected and App.ServiceProvider is null. This is a " +
-                "test-time wiring bug — the test must construct an " +
-                "IServiceProvider that registers SignaturePageViewModel.");
-        }
+        var sp = ResolveServices();
         return sp.GetRequiredService<SignaturePageViewModel>();
     }
 
+    private IServiceProvider ResolveServices()
+    {
+        return Services ?? (Application.Current as App)?.ServiceProvider ??
+            throw new InvalidOperationException(
+                "No IServiceProvider available for navigation. Inject one in tests " +
+                "or ensure App.ServiceProvider is initialized in production.");
+    }
+
 
     public MainPageViewModel()
     {
@@ -351,7 +351,7 @@ public partial class MainPageViewModel : ViewModelBase
     /// entry point is a SignalR push from Yavsc.Org ("devis
     /// received, sign here"); this command is the dev-time
     /// shortcut to reach the page without that infrastructure.
-    /// Aligned on the same nav-via-CurrentViewModel pattern as
+    /// Aligned on the same VM-first navigation pattern as
     /// <see cref="OpenSettings"/>: the VM resolves the target VM
     /// through <see cref="Services"/>, the <c>ViewLocator</c> picks
     /// the matching <c>Control</c> at bind time. No
@@ -359,14 +359,17 @@ public partial class MainPageViewModel : ViewModelBase
     /// access from the view layer.
     /// </summary>
     [RelayCommand]
-    internal void OpenSignatureDev()
+    internal async Task OpenSignatureDev()
     {
-        ((App)App.Current).PushPage(SignatureModel);
+        await ((App)App.Current!).PushPageAsync(SignatureModel).ConfigureAwait(true);
     }
 
-    private ViewModelBase? GetACLViewModel(BlogPostDto selectedPost)
+    private ViewModelBase GetACLViewModel(BlogPostDto selectedPost)
     {
-        throw new NotImplementedException();
+        var sp = ResolveServices();
+        var aclClient = sp.GetRequiredService<BlogAclApiClient>();
+        var circleClient = sp.GetRequiredService<CircleApiClient>();
+        return new PostAclDialogViewModel(selectedPost, aclClient, circleClient);
     }
 
     private async Task RefreshPostsAsync()
@@ -432,19 +435,16 @@ public partial class MainPageViewModel : ViewModelBase
 
 
     [RelayCommand(CanExecute = nameof(CanManageAcl))]
-    public void ManageAcl()
+    public async Task ManageAcl()
     {
         if (SelectedPost is null) return;
-        ((App)App.Current).PushPage(GetACLViewModel(SelectedPost));
+        await ((App)App.Current!).PushPageAsync(GetACLViewModel(SelectedPost)).ConfigureAwait(true);
     }
 
-    /// <summary>
-    /// Raised when the user asks to open the circles page (full
-    /// CRUD on their own circles). Same routing as
-    /// <see cref="ManageAclRequested"/>.
-    /// </summary>
-    public event EventHandler? OpenCirclesRequested;
-
     [RelayCommand]
-    public void OpenCircles() => OpenCirclesRequested?.Invoke(this, EventArgs.Empty);
+    public async Task OpenCircles()
+    {
+        var circlesVm = ResolveServices().GetRequiredService<CirclesPageViewModel>();
+        await ((App)App.Current!).PushPageAsync(circlesVm).ConfigureAwait(true);
+    }
 }

src/PostIt/PostIt/ViewModels/SessionStatusViewModel.cs

@@ -33,15 +33,6 @@ public partial class SessionStatusViewModel : ViewModelBase
     /// <c>HomePage</c> so the user lands on the blog editor.</summary>
     public event System.Action? LoginSucceeded;
 
-    /// <summary>Raised when the user clicks the "Paramètres" button on
-    /// the session banner. <c>App.axaml.cs</c> listens and pushes
-    /// <c>SettingsPage</c> (resolved from DI, bound to the canonical
-    /// <c>Settings</c> singleton) on top of the current navigation
-    /// stack. Same event pattern as <see cref="LogoutCompleted"/> and
-    /// <see cref="LoginSucceeded"/> so the VM stays decoupled from
-    /// <c>NavigationPage</c> / window lifetime.</summary>
-    public event System.Action? OpenSettingsRequested;
-
     [ObservableProperty]
     public partial bool IsLoggedIn { get; private set; }
 
@@ -145,10 +136,10 @@ public partial class SessionStatusViewModel : ViewModelBase
     }
 
     [RelayCommand]
-    internal void OpenSettings()
+    internal async Task OpenSettings()
     {
-        var app = (App)App.Current;
-        app.PushPage(app.ServiceProvider.GetRequiredService<Settings>());
+        var app = (App)App.Current!;
+        await app.PushPageAsync(app.ServiceProvider.GetRequiredService<Settings>()).ConfigureAwait(true);
     }
 
 }