Avalonia/tests/Avalonia.Layout.UnitTests/LayoutableTests.cs

using System;
using Avalonia.Controls;
using Moq;
using Xunit;

namespace Avalonia.Layout.UnitTests
{
    public class LayoutableTests
    {
        [Fact]
        public void Only_Calls_LayoutManager_InvalidateMeasure_Once()
        {
            var target = new Mock<ILayoutManager>();
            var control = new Decorator();
            var root = new LayoutTestRoot
            {
                Child = control,
                LayoutManager = target.Object,
            };

            root.Measure(Size.Infinity);
            root.Arrange(new Rect(root.DesiredSize));
            target.ResetCalls();

            control.InvalidateMeasure();
            control.InvalidateMeasure();

            target.Verify(x => x.InvalidateMeasure(control), Times.Once());
        }

        [Fact]
        public void Only_Calls_LayoutManager_InvalidateArrange_Once()
        {
            var target = new Mock<ILayoutManager>();
            var control = new Decorator();
            var root = new LayoutTestRoot
            {
                Child = control,
                LayoutManager = target.Object,
            };

            root.Measure(Size.Infinity);
            root.Arrange(new Rect(root.DesiredSize));
            target.ResetCalls();

            control.InvalidateArrange();
            control.InvalidateArrange();

            target.Verify(x => x.InvalidateArrange(control), Times.Once());
        }

        [Fact]
        public void Attaching_Control_To_Tree_Invalidates_Parent_Measure()
        {
            var target = new Mock<ILayoutManager>();
            var control = new Decorator();
            var root = new LayoutTestRoot
            {
                Child = control,
                LayoutManager = target.Object,
            };

            root.Measure(Size.Infinity);
            root.Arrange(new Rect(root.DesiredSize));
            Assert.True(control.IsMeasureValid);

            root.Child = null;
            root.Measure(Size.Infinity);
            root.Arrange(new Rect(root.DesiredSize));

            Assert.False(control.IsMeasureValid);
            Assert.True(root.IsMeasureValid);

            target.ResetCalls();

            root.Child = control;

            Assert.False(root.IsMeasureValid);
            Assert.False(control.IsMeasureValid);
            target.Verify(x => x.InvalidateMeasure(root), Times.Once());
        }
    }
}