Avalonia/tests/Avalonia.Markup.UnitTests/Data/TemplateBindingTests.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using Avalonia.Controls;
using Avalonia.Controls.Presenters;
using Avalonia.Controls.Primitives;
using Avalonia.Controls.Templates;
using Avalonia.Data;
using Avalonia.Data.Converters;
using Avalonia.UnitTests;
using Avalonia.VisualTree;
using Xunit;

namespace Avalonia.Markup.UnitTests.Data
{
    public class TemplateBindingTests
    {
        [Fact]
        public void OneWay_Binding_Should_Be_Set_Up()
        {
            var source = new Button
            {
                Template = new FuncControlTemplate<Button>((parent, _) =>
                    new ContentPresenter
                    {
                        [~ContentPresenter.ContentProperty] = new TemplateBinding(ContentControl.ContentProperty)
                    }),
            };

            source.ApplyTemplate();

            var target = (ContentPresenter)source.GetVisualChildren().Single();

            Assert.Null(target.Content);
            source.Content = "foo";
            Assert.Equal("foo", target.Content);
            source.Content = "bar";
            Assert.Equal("bar", target.Content);
        }

        [Fact]
        public void TwoWay_Binding_Should_Be_Set_Up()
        {
            var source = new Button
            {
                Template = new FuncControlTemplate<Button>((parent, _) =>
                    new ContentPresenter
                    {
                        [~ContentPresenter.ContentProperty] = new TemplateBinding(ContentControl.ContentProperty)
                        {
                            Mode = BindingMode.TwoWay,
                        }
                    }),
            };

            source.ApplyTemplate();

            var target = (ContentPresenter)source.GetVisualChildren().Single();

            Assert.Null(target.Content);
            source.Content = "foo";
            Assert.Equal("foo", target.Content);
            target.Content = "bar";
            Assert.Equal("bar", source.Content);
        }

        [Fact]
        public void Converter_Should_Be_Used()
        {
            var source = new Button
            {
                Template = new FuncControlTemplate<Button>((parent, _) =>
                    new ContentPresenter
                    {
                        [~ContentPresenter.ContentProperty] = new TemplateBinding(ContentControl.ContentProperty)
                        {
                            Mode = BindingMode.TwoWay,
                            Converter = new PrefixConverter(),
                            ConverterParameter = "Hello ",
                        }
                    }),
            };

            source.ApplyTemplate();

            var target = (ContentPresenter)source.GetVisualChildren().Single();

            Assert.Null(target.Content);
            source.Content = "foo";
            Assert.Equal("Hello foo", target.Content);
            target.Content = "Hello bar";
            Assert.Equal("bar", source.Content);
        }

        [Fact]
        public void Should_Work_Inside_Of_Tooltip()
        {
            using (UnitTestApplication.Start(TestServices.StyledWindow))
            {
                var window = new Window();
                var source = new Button
                {
                    Template = new FuncControlTemplate<Button>((parent, _) =>
                        new Decorator
                        {
                            [ToolTip.TipProperty] = new TextBlock
                            {
                                [~TextBlock.TextProperty] = new TemplateBinding(ContentControl.ContentProperty)
                            }
                        }),
                };

                window.Content = source;
                window.Show();
                try
                {
                    var templateChild = (Decorator)source.GetVisualChildren().Single();
                    ToolTip.SetIsOpen(templateChild, true);

                    var target = (TextBlock)ToolTip.GetTip(templateChild)!;

                    Assert.Null(target.Text);
                    source.Content = "foo";
                    Assert.Equal("foo", target.Text);
                    source.Content = "bar";
                    Assert.Equal("bar", target.Text);
                }
                finally
                {
                    window.Close();
                }
            }
        }

        [Fact]
        public void Should_Work_Inside_Of_Popup()
        {
            using (UnitTestApplication.Start(TestServices.StyledWindow))
            {
                var window = new Window();
                var source = new Button
                {
                    Template = new FuncControlTemplate<Button>((parent, _) =>
                        new Popup
                        {
                            Child = new TextBlock
                            {
                                [~TextBlock.TextProperty] = new TemplateBinding(ContentControl.ContentProperty)
                            }
                        }),
                };

                window.Content = source;
                window.Show();
                try
                {
                    var popup = (Popup)source.GetVisualChildren().Single();
                    popup.IsOpen = true;

                    var target = (TextBlock)popup.Child!;

                    target[~TextBlock.TextProperty] = new TemplateBinding(ContentControl.ContentProperty);
                    Assert.Null(target.Text);
                    source.Content = "foo";
                    Assert.Equal("foo", target.Text);
                    source.Content = "bar";
                    Assert.Equal("bar", target.Text);
                }
                finally
                {
                    window.Close();
                }
            }
        }

        [Fact]
        public void Should_Work_Inside_Of_Flyout()
        {
            using (UnitTestApplication.Start(TestServices.StyledWindow))
            {
                var window = new Window();
                var source = new Button
                {
                    Template = new FuncControlTemplate<Button>((parent, _) =>
                        new Button
                        {
                            Flyout = new Flyout
                            {
                                Content = new TextBlock
                                {
                                    [~TextBlock.TextProperty] = new TemplateBinding(ContentControl.ContentProperty)
                                }
                            }
                        }),
                };

                window.Content = source;
                window.Show();
                try
                {
                    var templateChild = (Button)source.GetVisualChildren().Single();
                    templateChild.Flyout!.ShowAt(templateChild);

                    var target = (TextBlock)((Flyout)templateChild.Flyout).Content!;

                    target[~TextBlock.TextProperty] = new TemplateBinding(ContentControl.ContentProperty);
                    Assert.Null(target.Text);
                    source.Content = "foo";
                    Assert.Equal("foo", target.Text);
                    source.Content = "bar";
                    Assert.Equal("bar", target.Text);
                }
                finally
                {
                    window.Close();
                }
            }
        }

        [Fact]
        public void Should_Not_Pass_UnsetValue_To_MultiBinding_During_ApplyTemplate()
        {
            var converter = new MultiConverter();
            var source = new Button
            {
                Content = "foo",
                Template = new FuncControlTemplate<Button>((parent, _) =>
                    new ContentPresenter
                    {
                        [~ContentPresenter.ContentProperty] = new MultiBinding
                        {
                            Converter = converter,
                            Bindings =
                            {
                                new TemplateBinding(ContentControl.ContentProperty),
                            }
                        }
                    }),
            };

            source.ApplyTemplate();

            var target = (ContentPresenter)source.GetVisualChildren().Single();

            // #8672 was caused by TemplateBinding passing "unset" to the MultiBinding during
            // ApplyTemplate as the TemplatedParent property doesn't get setup until after the
            // binding is initiated.
            Assert.Equal(new[] { "foo" }, converter.Values);
        }
        
        [Fact]
        public void Should_Execute_Converter_Without_Specific_TargetType()
        {
            // See https://github.com/AvaloniaUI/Avalonia/issues/9766
            var source = new Button
            {
                Template = new FuncControlTemplate<Button>((parent, _) =>
                    new ContentPresenter
                    {
                        [~ContentPresenter.IsVisibleProperty] = new MultiBinding
                        {
                            Converter = BoolConverters.And,
                            Bindings =
                            {
                                new TemplateBinding(ContentControl.ContentProperty)
                                {
                                    Converter = ObjectConverters.IsNotNull
                                }
                            }
                        }
                    }),
            };

            source.ApplyTemplate();

            var target = (ContentPresenter)source.GetVisualChildren().Single();

            Assert.False(target.IsVisible);
            source.Content = "foo";
            Assert.True(target.IsVisible);
        }

        private class PrefixConverter : IValueConverter
        {
            public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
            {
                if (value != null && parameter != null)
                {
                    return parameter.ToString() + value;
                }

                return null;
            }

            public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
            {
                if (value != null && parameter != null)
                {
                    var s = value.ToString();
                    var prefix = parameter.ToString();

                    if (s.StartsWith(prefix) == true)
                    {
                        return s.Substring(prefix.Length);
                    }

                    return s;
                }

                return null;
            }
        }

        private class MultiConverter : IMultiValueConverter
        {
            public List<object> Values { get; } = new();

            public object Convert(IList<object> values, Type targetType, object parameter, CultureInfo culture)
            {
                Values.AddRange(values);
                return values.FirstOrDefault();
            }
        }
    }
}