Don't self-register FontManager

src/Avalonia.Base/Media/FontManager.cs

@@ -44,26 +44,7 @@ public FontManager(IFontManagerImpl platformImpl)
         /// <summary>
         /// Get the current font manager instance.
         /// </summary>
-        public static FontManager Current
-        {
-            get
-            {
-                var current = AvaloniaLocator.Current.GetService<FontManager>();
-
-                if (current != null)
-                {
-                    return current;
-                }
-
-                var fontManagerImpl = AvaloniaLocator.Current.GetRequiredService<IFontManagerImpl>();
-
-                current = new FontManager(fontManagerImpl);
-
-                AvaloniaLocator.CurrentMutable.Bind<FontManager>().ToConstant(current);
-
-                return current;
-            }
-        }
+        public static FontManager Current => AvaloniaLocator.Current.GetRequiredService<FontManager>();
 
         /// <summary>
         ///     Gets the system's default font family.

src/Avalonia.Controls/Application.cs

@@ -278,8 +278,10 @@ public virtual void RegisterServices()
                 .Bind<IGlobalDataTemplates>().ToConstant(this)
                 .Bind<IGlobalStyles>().ToConstant(this)
                 .Bind<IThemeVariantHost>().ToConstant(this)
+                .Bind<FontManager>().ToLazy(() => new FontManager(
+                    AvaloniaLocator.Current.GetRequiredService<IFontManagerImpl>()))
                 .Bind<IInputManager>().ToConstant(InputManager)
-                .Bind< IToolTipService>().ToConstant(new ToolTipService(InputManager))
+                .Bind<IToolTipService>().ToConstant(new ToolTipService(InputManager))
                 .Bind<IKeyboardNavigationHandler>().ToTransient<KeyboardNavigationHandler>()
                 .Bind<IDragDropDevice>().ToConstant(DragDropDevice.Instance);
 

tests/Avalonia.Base.UnitTests/Media/FontManagerTests.cs

@@ -28,13 +28,17 @@ public void Should_Create_Single_Instance_Typeface()
         [Fact]
         public void Should_Throw_When_Default_FamilyName_Is_Null_And_Installed_Font_Family_Names_Is_Empty()
         {
-            using (UnitTestApplication.Start(TestServices.MockPlatformRenderInterface
-               .With(fontManagerImpl: new HeadlessFontManagerWithMultipleSystemFontsStub(
-                   installedFontFamilyNames: new string[] { },
-                   defaultFamilyName: null))))
+            // Wrap whole UnitTestApplication in the Assert.Throws, because disposal will try to access FontManager.Current again.
+            Assert.Throws<InvalidOperationException>(() =>
             {
-                Assert.Throws<InvalidOperationException>(() => FontManager.Current);
-            }
+                using (UnitTestApplication.Start(TestServices.MockPlatformRenderInterface
+                           .With(fontManagerImpl: new HeadlessFontManagerWithMultipleSystemFontsStub(
+                               installedFontFamilyNames: new string[] { },
+                               defaultFamilyName: null))))
+                {
+                    Assert.NotNull(FontManager.Current);
+                }
+            });
         }
 
         [Fact]

tests/Avalonia.RenderTests/TestRenderHelper.cs

@@ -41,13 +41,15 @@ static class TestRenderHelper
     static TestRenderHelper()
     {
 #if AVALONIA_SKIA
-        SkiaPlatform.Initialize();
+            SkiaPlatform.Initialize();
 #else
             Direct2D1Platform.Initialize();
 #endif
         AvaloniaLocator.CurrentMutable
             .Bind<IDispatcherImpl>()
-            .ToConstant(s_dispatcherImpl);
+            .ToConstant(s_dispatcherImpl)
+            .Bind<FontManager>().ToLazy(() => new FontManager(
+                AvaloniaLocator.Current.GetRequiredService<IFontManagerImpl>()));
 
         AvaloniaLocator.CurrentMutable.Bind<IAssetLoader>().ToConstant(new StandardAssetLoader());
     }

tests/Avalonia.UnitTests/UnitTestApplication.cs

@@ -73,19 +73,22 @@ public override void RegisterServices()
                 .Bind<IKeyboardNavigationHandler>().ToFunc(Services.KeyboardNavigation ?? (() => null))
                 .Bind<IRuntimePlatform>().ToConstant(Services.Platform)
                 .Bind<IPlatformRenderInterface>().ToConstant(Services.RenderInterface)
-                .Bind<IFontManagerImpl>().ToConstant(Services.FontManagerImpl)
                 .Bind<ITextShaperImpl>().ToConstant(Services.TextShaperImpl)
                 .Bind<IDispatcherImpl>().ToConstant(Services.DispatcherImpl)
                 .Bind<ICursorFactory>().ToConstant(Services.StandardCursorFactory)
                 .Bind<IWindowingPlatform>().ToConstant(Services.WindowingPlatform)
                 .Bind<PlatformHotkeyConfiguration>().ToSingleton<PlatformHotkeyConfiguration>()
                 .Bind<IPlatformSettings>().ToSingleton<DefaultPlatformSettings>()
-                .Bind<IAccessKeyHandler>().ToConstant(Services.AccessKeyHandler)
-                ;
-
-            // This is a hack to make tests work, we need to refactor the way font manager is registered
-            // See https://github.com/AvaloniaUI/Avalonia/issues/10081
-            AvaloniaLocator.CurrentMutable.Bind<FontManager>().ToConstant((FontManager)null!);
+                .Bind<IAccessKeyHandler>().ToConstant(Services.AccessKeyHandler);
+
+            if (Services.FontManagerImpl is not null)
+            {
+                AvaloniaLocator.CurrentMutable
+                    .Bind<IFontManagerImpl>().ToConstant(Services.FontManagerImpl)
+                    .Bind<FontManager>().ToLazy(() => new FontManager(
+                        AvaloniaLocator.Current.GetRequiredService<IFontManagerImpl>()));
+            }
+
             var theme = Services.Theme?.Invoke();
 
             if (theme is Style styles)