From be553738112175b1d291650a87fb32ac8fc7e2b5 Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Tue, 7 Jul 2020 15:52:30 -0300
Subject: [PATCH] add some unit tests and tidy relative panel

---
 src/Avalonia.Controls/RelativePanel.cs        | 33 +++++++++++++++++--
 .../RelativePanelTests.cs                     | 32 ++++++++++++++++++
 2 files changed, 63 insertions(+), 2 deletions(-)
 create mode 100644 tests/Avalonia.Controls.UnitTests/RelativePanelTests.cs

diff --git a/src/Avalonia.Controls/RelativePanel.cs b/src/Avalonia.Controls/RelativePanel.cs
index cf7fa212fd..73f668bbe9 100644
--- a/src/Avalonia.Controls/RelativePanel.cs
+++ b/src/Avalonia.Controls/RelativePanel.cs
@@ -60,12 +60,26 @@ namespace Avalonia.Controls
             {
                 child.Measure(availableSize);
             }
+
+            Rect bounds = new Rect();
+
             foreach (var item in CalculateLocations(availableSize))
             {
                 if (item.Item2.Size.Width < item.Item1.DesiredSize.Width || item.Item2.Size.Height < item.Item1.DesiredSize.Height)
                     item.Item1.Measure(item.Item2.Size);
+
+                if(item.Item2.Right > bounds.Width)
+                {
+                    bounds = bounds.WithWidth(item.Item2.Right);
+                }
+
+                if(item.Item2.Bottom > bounds.Height)
+                {
+                    bounds = bounds.WithHeight(item.Item2.Bottom);
+                }
             }
-            return base.MeasureOverride(availableSize);
+
+            return bounds.Size;
         }
 
         /// <summary>
@@ -79,9 +93,24 @@ namespace Avalonia.Controls
         /// <returns>The actual size used.</returns>
         protected override Size ArrangeOverride(Size finalSize)
         {
+            Rect bounds = new Rect();
+
             foreach (var item in CalculateLocations(finalSize))
+            {
                 item.Item1.Arrange(item.Item2);
-            return finalSize;
+
+                if (item.Item2.Right > bounds.Width)
+                {
+                    bounds = bounds.WithWidth(item.Item2.Right);
+                }
+
+                if (item.Item2.Bottom > bounds.Height)
+                {
+                    bounds = bounds.WithHeight(item.Item2.Bottom);
+                }
+            }            
+            
+            return bounds.Size;
         }
 
         private IEnumerable<Tuple<ILayoutable, Rect>> CalculateLocations(Size finalSize)
diff --git a/tests/Avalonia.Controls.UnitTests/RelativePanelTests.cs b/tests/Avalonia.Controls.UnitTests/RelativePanelTests.cs
new file mode 100644
index 0000000000..7a2036687e
--- /dev/null
+++ b/tests/Avalonia.Controls.UnitTests/RelativePanelTests.cs
@@ -0,0 +1,32 @@
+using Avalonia.Controls.Shapes;
+using Xunit;
+
+namespace Avalonia.Controls.UnitTests
+{
+    public class RelativePanelTests
+    {
+        [Fact]
+        public void Lays_Out_1_Child_Below_the_other()
+        {
+            var rect1 = new Rectangle { Height = 20, Width = 20 };
+            var rect2 = new Rectangle { Height = 20, Width = 20 };
+
+            var target = new RelativePanel
+            {
+                Children =
+                {
+                    rect1, rect2
+                }
+            };
+
+            RelativePanel.SetAlignLeftWithPanel(rect1 , true);
+            RelativePanel.SetBelow(rect2, rect1);
+            target.Measure(new Size(400, 400));
+            target.Arrange(new Rect(target.DesiredSize));
+
+            Assert.Equal(new Size(20, 40), target.Bounds.Size);
+            Assert.Equal(new Rect(0, 0, 20, 20), target.Children[0].Bounds);
+            Assert.Equal(new Rect(0, 20, 20, 20), target.Children[1].Bounds);
+        }
+    }
+}