Added failing tests for #3796.

tests/Avalonia.Controls.UnitTests/Primitives/PopupRootTests.cs

@@ -2,12 +2,14 @@ using System;
 using System.Linq;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Primitives.PopupPositioning;
 using Avalonia.Controls.Templates;
 using Avalonia.LogicalTree;
 using Avalonia.Platform;
 using Avalonia.Styling;
 using Avalonia.UnitTests;
 using Avalonia.VisualTree;
+using Moq;
 using Xunit;
 
 namespace Avalonia.Controls.UnitTests.Primitives
@@ -216,12 +218,10 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var window = new Window();
                 var popupImpl = MockWindowingPlatform.CreatePopupMock(window.PlatformImpl);
 
-                popupImpl.Setup(x => x.ClientSize).Returns(new Size(400, 480));
-
                 var child = new Canvas
                 {
                     Width = 400,
-                    Height = 800,
+                    Height = 1344,
                 };
 
                 var target = CreateTarget(window, popupImpl.Object);
@@ -229,7 +229,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
                 target.Show();
 
-                Assert.Equal(new Size(400, 480), target.Bounds.Size);
+                Assert.Equal(new Size(400, 1024), target.Bounds.Size);
 
                 // Issue #3784 causes this to be (0, 160) which makes no sense as Window has no
                 // parent control to be offset against.
@@ -237,6 +237,61 @@ namespace Avalonia.Controls.UnitTests.Primitives
             }
         }
 
+        [Fact]
+        public void MinWidth_MinHeight_Should_Be_Respected()
+        {
+            // Issue #3796
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var window = new Window();
+                var popupImpl = MockWindowingPlatform.CreatePopupMock(window.PlatformImpl);
+
+                var target = CreateTarget(window, popupImpl.Object);
+                target.MinWidth = 400;
+                target.MinHeight = 800;
+                target.Content = new Border
+                {
+                    Width = 100,
+                    Height = 100,
+                };
+
+                target.Show();
+
+                Assert.Equal(new Rect(0, 0, 400, 800), target.Bounds);
+                Assert.Equal(new Size(400, 800), target.ClientSize);
+                Assert.Equal(new Size(400, 800), target.PlatformImpl.ClientSize);
+            }
+        }
+
+        [Fact]
+        public void Setting_Width_Should_Resize_WindowImpl()
+        {
+            // Issue #3796
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var window = new Window();
+                var popupImpl = MockWindowingPlatform.CreatePopupMock(window.PlatformImpl);
+                var positioner = new Mock<IPopupPositioner>();
+                popupImpl.Setup(x => x.PopupPositioner).Returns(positioner.Object);
+
+                var target = CreateTarget(window, popupImpl.Object);
+                target.Width = 400;
+                target.Height = 800;
+
+                target.Show();
+
+                Assert.Equal(400, target.Width);
+                Assert.Equal(800, target.Height);
+
+                target.Width = 410;
+                target.LayoutManager.ExecuteLayoutPass();
+
+                positioner.Verify(x => 
+                    x.Update(It.Is<PopupPositionerParameters>(x => x.Size.Width == 410)));
+                Assert.Equal(410, target.Width);
+            }
+        }
+
         private PopupRoot CreateTarget(TopLevel popupParent, IPopupImpl impl = null)
         {
             impl ??= popupParent.PlatformImpl.CreatePopup();

tests/Avalonia.Controls.UnitTests/WindowTests.cs

@@ -514,6 +514,32 @@ namespace Avalonia.Controls.UnitTests
             }
         }
 
+        [Fact]
+        public void Setting_Width_Should_Resize_WindowImpl()
+        {
+            // Issue #3796
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var target = new Window()
+                {
+                    Width = 400,
+                    Height = 800,
+                };
+
+                target.Show();
+
+                Assert.Equal(400, target.Width);
+                Assert.Equal(800, target.Height);
+
+                target.Width = 410;
+                target.LayoutManager.ExecuteLayoutPass();
+
+                var windowImpl = Mock.Get(target.PlatformImpl);
+                windowImpl.Verify(x => x.Resize(new Size(410, 800)));
+                Assert.Equal(410, target.Width);
+            }
+        }
+
         private IWindowImpl CreateImpl(Mock<IRenderer> renderer)
         {
             return Mock.Of<IWindowImpl>(x =>

tests/Avalonia.UnitTests/MockWindowingPlatform.cs

@@ -66,15 +66,19 @@ namespace Avalonia.UnitTests
         public static Mock<IPopupImpl> CreatePopupMock(IWindowBaseImpl parent)
         {
             var popupImpl = new Mock<IPopupImpl>();
+            var clientSize = new Size();
 
             var positionerHelper = new ManagedPopupPositionerPopupImplHelper(parent, (pos, size, scale) =>
             {
+                clientSize = size.Constrain(s_screenSize);
                 popupImpl.Object.PositionChanged?.Invoke(pos);
-                popupImpl.Object.Resized?.Invoke(size);
+                popupImpl.Object.Resized?.Invoke(clientSize);
             });
             
             var positioner = new ManagedPopupPositioner(positionerHelper);
 
+            popupImpl.SetupAllProperties();
+            popupImpl.Setup(x => x.ClientSize).Returns(() => clientSize);
             popupImpl.Setup(x => x.Scaling).Returns(1);
             popupImpl.Setup(x => x.PopupPositioner).Returns(positioner);