add unit tests for layout queue

src/Avalonia.Layout/Properties/AssemblyInfo.cs

@@ -1,6 +1,10 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using System.Runtime.CompilerServices;
 using Avalonia.Metadata;
 
+[assembly: InternalsVisibleTo("Avalonia.Layout.UnitTests")]
+
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Layout")]
+

tests/Avalonia.Layout.UnitTests/LayoutQueueTests.cs

@@ -0,0 +1,196 @@
+using System.Collections.Generic;
+using System.Linq;
+using Xunit;
+
+namespace Avalonia.Layout.UnitTests
+{
+    public class LayoutQueueTests
+    {
+        [Fact]
+        public void Should_Enqueue()
+        {
+            var target = new LayoutQueue<string>(_ => true);
+            var refQueue = new Queue<string>();
+            var items = new[] { "1", "2", "3" };
+
+            foreach (var item in items)
+            {
+                target.Enqueue(item);
+                refQueue.Enqueue(item);
+            }
+
+            Assert.Equal(refQueue, target);
+        }
+
+        [Fact]
+        public void Should_Dequeue()
+        {
+            var target = new LayoutQueue<string>(_ => true);
+            var refQueue = new Queue<string>();
+            var items = new[] { "1", "2", "3" };
+
+            foreach (var item in items)
+            {
+                target.Enqueue(item);
+                refQueue.Enqueue(item);
+            }
+
+            while (refQueue.Count > 0)
+            {
+                Assert.Equal(refQueue.Dequeue(), target.Dequeue());
+            }
+        }
+
+        [Fact]
+        public void Should_Enqueue_UniqueElements()
+        {
+            var target = new LayoutQueue<string>(_ => true);
+
+            var items = new[] { "1", "2", "3", "1" };
+
+            foreach (var item in items)
+            {
+                target.Enqueue(item);
+            }
+
+            Assert.Equal(3, target.Count);
+            Assert.Equal(items.Take(3), target);
+        }
+
+        [Fact]
+        public void Shouldnt_Enqueue_More_Than_Limit_In_Loop()
+        {
+            var target = new LayoutQueue<string>(_ => true);
+
+            //1
+            target.Enqueue("Foo");
+
+            Assert.Equal(1, target.Count);
+
+            target.BeginLoop(3);
+
+            target.Dequeue();
+
+            //2
+            target.Enqueue("Foo");
+            target.Dequeue();
+
+            //3
+            target.Enqueue("Foo");
+
+            Assert.Equal(1, target.Count);
+
+            target.Dequeue();
+
+            //4 more than limit shouldn't be added
+            target.Enqueue("Foo");
+
+            Assert.Equal(0, target.Count);
+        }
+
+        [Fact]
+        public void Shouldnt_Count_Unique_Enqueue_For_Limit_In_Loop()
+        {
+            var target = new LayoutQueue<string>(_ => true);
+
+            //1
+            target.Enqueue("Foo");
+
+            Assert.Equal(1, target.Count);
+
+            target.BeginLoop(3);
+
+            target.Dequeue();
+
+            //2
+            target.Enqueue("Foo");
+            target.Enqueue("Foo");
+            target.Dequeue();
+
+            //3
+            target.Enqueue("Foo");
+            target.Enqueue("Foo");
+
+            Assert.Equal(1, target.Count);
+
+            target.Dequeue();
+
+            //4 more than limit shouldn't be added
+            target.Enqueue("Foo");
+
+            Assert.Equal(0, target.Count);
+        }
+
+        [Fact]
+        public void Should_Enqueue_When_Condition_True_After_Loop_When_Limit_Met()
+        {
+            var target = new LayoutQueue<string>(_ => true);
+
+            //1
+            target.Enqueue("Foo");
+
+            Assert.Equal(1, target.Count);
+
+            target.BeginLoop(3);
+
+            target.Dequeue();
+
+            //2
+            target.Enqueue("Foo");
+            target.Dequeue();
+
+            //3
+            target.Enqueue("Foo");
+
+            Assert.Equal(1, target.Count);
+
+            target.Dequeue();
+
+            //4 more than limit shouldn't be added to queue
+            target.Enqueue("Foo");
+
+            Assert.Equal(0, target.Count);
+
+            target.EndLoop();
+
+            //after loop should be added once
+            Assert.Equal(1, target.Count);
+            Assert.Equal("Foo", target.First());
+        }
+
+        [Fact]
+        public void Shouldnt_Enqueue_When_Condition_False_After_Loop_When_Limit_Met()
+        {
+            var target = new LayoutQueue<string>(_ => false);
+
+            //1
+            target.Enqueue("Foo");
+
+            Assert.Equal(1, target.Count);
+
+            target.BeginLoop(3);
+
+            target.Dequeue();
+
+            //2
+            target.Enqueue("Foo");
+            target.Dequeue();
+
+            //3
+            target.Enqueue("Foo");
+
+            Assert.Equal(1, target.Count);
+
+            target.Dequeue();
+
+            //4 more than limit shouldn't be added
+            target.Enqueue("Foo");
+
+            Assert.Equal(0, target.Count);
+
+            target.EndLoop();
+
+            Assert.Equal(0, target.Count);
+        }
+    }
+}