Fix init order of SetupWithClassicDesktopLifetime (#21954)

* Fix init order of SetupWithClassicDesktopLifetime

* Don't raise Startup in Setup

* Fix warning

src/Avalonia.Controls/AppBuilder.cs

@@ -353,12 +353,21 @@ namespace Avalonia
             SetupUnsafe();
         }
 
+        /// <summary>
+        /// Allows <see cref="Setup"/> to be called again after it has already been called once.
+        /// </summary>
+        internal static void ResetSetupForUnitTests()
+            => s_setupWasAlreadyCalled = false;
+
         /// <summary>
         /// Setup method that doesn't check for input initalizers being set.
         /// Nor 
         /// </summary>
         internal void SetupUnsafe()
         {
+            var setupLifetime = _lifetime as ISetupApplicationLifetime;
+            setupLifetime?.BeforeAppInit();
+
             _optionsInitializers?.Invoke();
             RuntimePlatformServicesInitializer?.Invoke();
             TextShapingSubsystemInitializer?.Invoke();
@@ -373,6 +382,8 @@ namespace Avalonia
             AfterApplicationSetupCallback?.Invoke(Self);
             AfterSetupCallback?.Invoke(Self);
             Instance.OnFrameworkInitializationCompleted();
+
+            setupLifetime?.AfterAppInit();
         }
     }
 }

src/Avalonia.Controls/ApplicationLifetimes/ClassicDesktopStyleApplicationLifetime.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using Avalonia.Collections;
@@ -12,13 +13,19 @@ using Avalonia.Threading;
 
 namespace Avalonia.Controls.ApplicationLifetimes
 {
-    public class ClassicDesktopStyleApplicationLifetime : IClassicDesktopStyleApplicationLifetime, IDisposable
+    public class ClassicDesktopStyleApplicationLifetime :
+        IClassicDesktopStyleApplicationLifetime,
+        ISetupApplicationLifetime,
+        IDisposable
     {
         private int _exitCode;
         private CancellationTokenSource? _cts;
         private bool _isShuttingDown;
         private readonly AvaloniaList<Window> _windows = new();
-        private CompositeDisposable? _compositeDisposable; 
+        private CompositeDisposable? _globalEventsSubscriptions;
+        private bool _beforeInitCalled;
+        private bool _afterInitCalled;
+        private IPlatformLifetimeEventsImpl? _platformLifetimeEventsImpl;
 
         /// <inheritdoc/>
         public event EventHandler<ControlledApplicationLifetimeStartupEventArgs>? Startup;
@@ -67,16 +74,11 @@ namespace Avalonia.Controls.ApplicationLifetimes
             return DoShutdown(new ShutdownRequestedEventArgs(), true, false, exitCode);
         }
 
-        internal void SubscribeGlobalEvents()
+        private void SubscribeGlobalEvents()
         {
-            if (_compositeDisposable is not null)
-            {
-                // There could be a case, when lifetime was setup without starting.
-                // Until developer started it manually later. To avoid API breaking changes, it will execute Setup method twice.
-                return;
-            }
+            Debug.Assert(_globalEventsSubscriptions is null);
 
-            _compositeDisposable = new CompositeDisposable(
+            _globalEventsSubscriptions = new CompositeDisposable(
                 Window.WindowOpenedEvent.AddClassHandler(typeof(Window), (sender, _) =>
                 {
                     var window = (Window)sender!;
@@ -93,16 +95,32 @@ namespace Avalonia.Controls.ApplicationLifetimes
                 }));            
         }
 
-        internal void SetupCore(string[] args)
+        private void BeforeInit()
         {
+            if (_beforeInitCalled)
+                return;
+
+            _beforeInitCalled = true;
             SubscribeGlobalEvents();
+        }
 
-            Startup?.Invoke(this, new ControlledApplicationLifetimeStartupEventArgs(args));
+        void ISetupApplicationLifetime.BeforeAppInit()
+            => BeforeInit();
 
-            var lifetimeEvents = AvaloniaLocator.Current.GetService<IPlatformLifetimeEventsImpl>(); 
+        private void AfterInit()
+        {
+            if (_afterInitCalled)
+                return;
 
-            if (lifetimeEvents != null)
-                lifetimeEvents.ShutdownRequested += OnShutdownRequested;
+            _afterInitCalled = true;
+
+            _platformLifetimeEventsImpl = AvaloniaLocator.Current.GetService<IPlatformLifetimeEventsImpl>();
+            _platformLifetimeEventsImpl?.ShutdownRequested += OnShutdownRequested;
+        }
+
+        void ISetupApplicationLifetime.AfterAppInit()
+        {
+            AfterInit();
         }
 
         public int Start(string[] args)
@@ -121,7 +139,11 @@ namespace Avalonia.Controls.ApplicationLifetimes
 
         internal int StartCore(string[] args)
         {
-            SetupCore(args);
+            // Before/AfterInit should have been called from ISetupApplicationLifetime.
+            // If somehow they weren't (e.g., for a manually started lifetime), do it now.
+            BeforeInit();
+            AfterInit();
+            Startup?.Invoke(this, new ControlledApplicationLifetimeStartupEventArgs(args));
 
             _cts = new CancellationTokenSource();
 
@@ -143,8 +165,11 @@ namespace Avalonia.Controls.ApplicationLifetimes
 
         public void Dispose()
         {
-            _compositeDisposable?.Dispose();
-            _compositeDisposable = null;
+            _globalEventsSubscriptions?.Dispose();
+            _globalEventsSubscriptions = null;
+
+            _platformLifetimeEventsImpl?.ShutdownRequested -= OnShutdownRequested;
+            _platformLifetimeEventsImpl = null;
         }
 
         private bool DoShutdown(
@@ -222,15 +247,12 @@ namespace Avalonia
     /// </summary>
     public static class ClassicDesktopStyleApplicationLifetimeExtensions
     {
-        private static ClassicDesktopStyleApplicationLifetime PrepareLifetime(AppBuilder builder, string[] args,
+        private static ClassicDesktopStyleApplicationLifetime CreateLifetime(
+            string[] args,
             Action<IClassicDesktopStyleApplicationLifetime>? lifetimeBuilder)
         {
-            var lifetime = new ClassicDesktopStyleApplicationLifetime();
-            lifetime.SubscribeGlobalEvents();
-
-            lifetime.Args = args;
+            var lifetime = new ClassicDesktopStyleApplicationLifetime { Args = args };
             lifetimeBuilder?.Invoke(lifetime);
-
             return lifetime;
         }
 
@@ -244,8 +266,7 @@ namespace Avalonia
         public static AppBuilder SetupWithClassicDesktopLifetime(this AppBuilder builder, string[] args,
             Action<IClassicDesktopStyleApplicationLifetime>? lifetimeBuilder = null)
         {
-            var lifetime = PrepareLifetime(builder, args, lifetimeBuilder);
-            lifetime.SetupCore(args);
+            var lifetime = CreateLifetime(args, lifetimeBuilder);
             return builder.SetupWithLifetime(lifetime);
         }
 
@@ -260,7 +281,7 @@ namespace Avalonia
             this AppBuilder builder, string[] args,
             Action<IClassicDesktopStyleApplicationLifetime>? lifetimeBuilder = null)
         {
-            var lifetime = PrepareLifetime(builder, args, lifetimeBuilder);
+            var lifetime = CreateLifetime(args, lifetimeBuilder);
             builder.SetupWithLifetime(lifetime);
             return lifetime.Start(args);
         }
@@ -275,7 +296,7 @@ namespace Avalonia
         public static int StartWithClassicDesktopLifetime(
             this AppBuilder builder, string[] args, ShutdownMode shutdownMode)
         {
-            var lifetime = PrepareLifetime(builder, args, l => l.ShutdownMode = shutdownMode);
+            var lifetime = CreateLifetime(args, l => l.ShutdownMode = shutdownMode);
             builder.SetupWithLifetime(lifetime);
             return lifetime.Start(args);
         }

src/Avalonia.Controls/ApplicationLifetimes/ISetupApplicationLifetime.cs

@@ -0,0 +1,17 @@
+namespace Avalonia.Controls.ApplicationLifetimes;
+
+/// <summary>
+/// An interface for lifetimes that need to execute extra code before and after initialization.
+/// </summary>
+internal interface ISetupApplicationLifetime
+{
+    /// <summary>
+    /// Called before anything is initialized: platforms, rendering, app, etc. aren't available yet.
+    /// </summary>
+    void BeforeAppInit();
+
+    /// <summary>
+    /// Called after the app has been initialized.
+    /// </summary>
+    void AfterAppInit();
+}

tests/Avalonia.Controls.UnitTests/DesktopStyleApplicationLifetimeTests.cs

@@ -1,11 +1,7 @@
 using System;
 using System.Collections.Generic;
-using System.Threading;
 using Avalonia.Controls.ApplicationLifetimes;
-using Avalonia.Controls.Platform;
 using Avalonia.Platform;
-using Avalonia.Rendering;
-using Avalonia.Rendering.Composition;
 using Avalonia.Threading;
 using Avalonia.UnitTests;
 using Moq;
@@ -13,25 +9,15 @@ using Xunit;
 
 namespace Avalonia.Controls.UnitTests
 {
-    
     public class DesktopStyleApplicationLifetimeTests : ScopedTestBase
     {
-        IDispatcherImpl CreateDispatcherWithInstantMainLoop()
-        {
-            var mock = new Mock<IControlledDispatcherImpl>();
-            mock.Setup(x => x.RunLoop(It.IsAny<CancellationToken>()))
-                .Callback(() => Dispatcher.UIThread.ExitAllFrames());
-            mock.Setup(x => x.CurrentThreadIsLoopThread).Returns(true);
-            return mock.Object;
-        }
-        
         [Fact]
         public void Should_Set_ExitCode_After_Shutdown()
         {
             using (UnitTestApplication.Start(new TestServices()))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())    
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 Dispatcher.UIThread.Post(() => lifetime.Shutdown(1337));
                 var exitCode = lifetime.Start(Array.Empty<string>());
@@ -47,7 +33,7 @@ namespace Avalonia.Controls.UnitTests
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var windows = new List<Window> { new Window(), new Window(), new Window(), new Window() };
 
@@ -69,7 +55,7 @@ namespace Avalonia.Controls.UnitTests
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
                 lifetime.ShutdownMode = ShutdownMode.OnExplicitShutdown;
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
 
@@ -104,7 +90,7 @@ namespace Avalonia.Controls.UnitTests
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
                 lifetime.ShutdownMode = ShutdownMode.OnMainWindowClose;
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
 
@@ -133,7 +119,7 @@ namespace Avalonia.Controls.UnitTests
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
                 lifetime.ShutdownMode = ShutdownMode.OnMainWindowClose;
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
                 var secondaryWindowClosingExecuted = false;
@@ -173,7 +159,7 @@ namespace Avalonia.Controls.UnitTests
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
                 lifetime.ShutdownMode = ShutdownMode.OnMainWindowClose;
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
                 var secondaryWindowClosingExecuted = false;
@@ -213,7 +199,7 @@ namespace Avalonia.Controls.UnitTests
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
                 lifetime.ShutdownMode = ShutdownMode.OnLastWindowClose;
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
 
@@ -243,7 +229,7 @@ namespace Avalonia.Controls.UnitTests
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var window = new Window();
 
@@ -259,7 +245,7 @@ namespace Avalonia.Controls.UnitTests
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var window = new Window();
 
@@ -279,7 +265,7 @@ namespace Avalonia.Controls.UnitTests
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var window = new Window();
 
@@ -311,7 +297,7 @@ namespace Avalonia.Controls.UnitTests
             using (UnitTestApplication.Start(services))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var window = new Window();
 
@@ -361,7 +347,7 @@ namespace Avalonia.Controls.UnitTests
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
                 lifetime.ShutdownMode = ShutdownMode.OnMainWindowClose;
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
 
@@ -399,7 +385,7 @@ namespace Avalonia.Controls.UnitTests
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
                 lifetime.ShutdownMode = ShutdownMode.OnLastWindowClose;
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
 
@@ -438,7 +424,7 @@ namespace Avalonia.Controls.UnitTests
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 lifetime.Exit += (_, _) => Assert.Fail("lifetime.Exit was called.");
                 Dispatcher.UIThread.ShutdownStarted += UiThreadOnShutdownStarted;
@@ -478,7 +464,7 @@ namespace Avalonia.Controls.UnitTests
             using (UnitTestApplication.Start(TestServices.StyledWindow.With()))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
                 var closingRaised = 0;
@@ -518,7 +504,7 @@ namespace Avalonia.Controls.UnitTests
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
             {
-                lifetime.SetupCore(Array.Empty<string>());
+                Setup(lifetime);
 
                 var hasExit = false;
 
@@ -537,5 +523,130 @@ namespace Avalonia.Controls.UnitTests
                 Assert.True(hasExit);
             }
         }
+
+        [Fact]
+        public void SetupWithClassicDesktopLifetime_Should_Subscribe_To_Platform_ShutdownRequested()
+        {
+            var lifetimeEvents = new Mock<IPlatformLifetimeEventsImpl>();
+            ClassicDesktopStyleApplicationLifetime? lifetime = null;
+
+            CreateAppBuilder(lifetimeEvents.Object).SetupWithClassicDesktopLifetime(
+                [],
+                l => lifetime = (ClassicDesktopStyleApplicationLifetime)l);
+
+            Assert.NotNull(lifetime);
+
+            using (lifetime)
+            {
+                var window = new Window();
+                window.Show();
+
+                var raised = 0;
+
+                lifetime.ShutdownRequested += (_, e) =>
+                {
+                    e.Cancel = true;
+                    ++raised;
+                };
+
+                lifetimeEvents.Raise(x => x.ShutdownRequested += null, new ShutdownRequestedEventArgs());
+
+                Assert.Equal(1, raised);
+                Assert.Equal([window], lifetime.Windows);
+            }
+        }
+
+        [Fact]
+        public void SetupWithClassicDesktopLifetime_Should_Not_Raise_Startup()
+        {
+            var frameworkInitCalled = false;
+            var lifetimeBuilderCalled = false;
+            var startupRaised = false;
+
+            CreateAppBuilder(onFrameworkInitializationCompleted: () => frameworkInitCalled = true)
+                .SetupWithClassicDesktopLifetime(
+                    ["foo", "bar"],
+                    l =>
+                    {
+                        lifetimeBuilderCalled = true;
+                        l.Startup += (_, _) => startupRaised = true;
+                    });
+
+            Assert.True(frameworkInitCalled);
+            Assert.True(lifetimeBuilderCalled);
+            Assert.False(startupRaised);
+        }
+
+        [Fact]
+        public void Start_After_SetupWithClassicDesktopLifetime_Should_Not_Raise_Startup_Twice()
+        {
+            ClassicDesktopStyleApplicationLifetime? lifetime = null;
+            var raised = 0;
+
+            CreateAppBuilder().SetupWithClassicDesktopLifetime(
+                [],
+                l =>
+                {
+                    lifetime = (ClassicDesktopStyleApplicationLifetime)l;
+                    l.Startup += (_, _) => ++raised;
+                });
+
+            Assert.NotNull(lifetime);
+
+            using (lifetime)
+            {
+                Assert.Equal(0, raised);
+
+                Dispatcher.UIThread.Post(Dispatcher.UIThread.ExitAllFrames);
+                lifetime.Start([]);
+
+                Assert.Equal(1, raised);
+            }
+        }
+
+        private static void Setup(ClassicDesktopStyleApplicationLifetime lifetime)
+        {
+            ISetupApplicationLifetime setupLifetime = lifetime;
+            setupLifetime.BeforeAppInit();
+            setupLifetime.AfterAppInit();
+        }
+
+        private static AppBuilder CreateAppBuilder(
+            IPlatformLifetimeEventsImpl? platformLifetimeEvents = null,
+            Action? onFrameworkInitializationCompleted = null)
+        {
+            AppBuilder.ResetSetupForUnitTests();
+
+            return AppBuilder.Configure(() => new SetupTestApplication(onFrameworkInitializationCompleted))
+                .UseRuntimePlatformSubsystem(() => { })
+                .UseRenderingSubsystem(() => { })
+                .UseTextShapingSubsystem(() => { })
+                .UseWindowingSubsystem(() =>
+                {
+                    if (platformLifetimeEvents is not null)
+                        AvaloniaLocator.CurrentMutable.Bind<IPlatformLifetimeEventsImpl>().ToConstant(platformLifetimeEvents);
+                });
+        }
+
+        private sealed class SetupTestApplication(Action? onFrameworkInitializationCompleted)
+            : UnitTestApplication(TestServices.StyledWindow)
+        {
+            private bool _servicesRegistered;
+
+            public override void RegisterServices()
+            {
+                if (_servicesRegistered)
+                    return;
+
+                _servicesRegistered = true;
+                base.RegisterServices();
+            }
+
+            public override void OnFrameworkInitializationCompleted()
+            {
+                base.OnFrameworkInitializationCompleted();
+                onFrameworkInitializationCompleted?.Invoke();
+            }
+        }
     }
 }