Avalonia/tests/Avalonia.Base.UnitTests/Data/Core/ExpressionObserverTests_Negation.cs

// 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;
using System.Reactive.Linq;
using System.Threading.Tasks;
using Avalonia.Data;
using Avalonia.Data.Core;
using Xunit;

namespace Avalonia.Base.UnitTests.Data.Core
{
    public class ExpressionObserverTests_Negation
    {
        [Fact]
        public async Task Should_Negate_Boolean_Value()
        {
            var data = new { Foo = true };
            var target = new ExpressionObserver(data, "!Foo");
            var result = await target.Take(1);

            Assert.False((bool)result);

            GC.KeepAlive(data);
        }

        [Fact]
        public async Task Should_Negate_0()
        {
            var data = new { Foo = 0 };
            var target = new ExpressionObserver(data, "!Foo");
            var result = await target.Take(1);

            Assert.True((bool)result);

            GC.KeepAlive(data);
        }

        [Fact]
        public async Task Should_Negate_1()
        {
            var data = new { Foo = 1 };
            var target = new ExpressionObserver(data, "!Foo");
            var result = await target.Take(1);

            Assert.False((bool)result);

            GC.KeepAlive(data);
        }

        [Fact]
        public async Task Should_Negate_False_String()
        {
            var data = new { Foo = "false" };
            var target = new ExpressionObserver(data, "!Foo");
            var result = await target.Take(1);

            Assert.True((bool)result);

            GC.KeepAlive(data);
        }

        [Fact]
        public async Task Should_Negate_True_String()
        {
            var data = new { Foo = "True" };
            var target = new ExpressionObserver(data, "!Foo");
            var result = await target.Take(1);

            Assert.False((bool)result);

            GC.KeepAlive(data);
        }

        [Fact]
        public async Task Should_Return_BindingNotification_For_String_Not_Convertible_To_Boolean()
        {
            var data = new { Foo = "foo" };
            var target = new ExpressionObserver(data, "!Foo");
            var result = await target.Take(1);

            Assert.Equal(
                new BindingNotification(
                    new InvalidCastException($"Unable to convert 'foo' to bool."),
                    BindingErrorType.Error), 
                result);

            GC.KeepAlive(data);
        }

        [Fact]
        public async Task Should_Return_BindingNotification_For_Value_Not_Convertible_To_Boolean()
        {
            var data = new { Foo = new object() };
            var target = new ExpressionObserver(data, "!Foo");
            var result = await target.Take(1);

            Assert.Equal(
                new BindingNotification(
                    new InvalidCastException($"Unable to convert 'System.Object' to bool."),
                    BindingErrorType.Error),
                result);

            GC.KeepAlive(data);
        }

        [Fact]
        public void SetValue_Should_Return_False_For_Invalid_Value()
        {
            var data = new { Foo = "foo" };
            var target = new ExpressionObserver(data, "!Foo");
            target.Subscribe(_ => { });

            Assert.False(target.SetValue("bar"));

            GC.KeepAlive(data);
        }

        [Fact]
        public void Can_SetValue_For_Valid_Value()
        {
            var data = new Test { Foo = true };
            var target = new ExpressionObserver(data, "!Foo");
            target.Subscribe(_ => { });

            Assert.True(target.SetValue(true));

            Assert.False(data.Foo);
        }

        private class Test
        {
            public bool Foo { get; set; }
        }
    }
}