// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System.Collections.Generic;
using Roslyn.Test.Utilities;
using Xunit;
 
namespace Microsoft.CodeAnalysis.UnitTests.UtilityTest;
 
public class WeakEventTests
{
    [Fact]
    public void AddAndRemove()
    {
        var e = new WeakEvent<int>();
 
        var sender = new object();
        var target = new List<int>();
        var handler1 = new WeakEventHandler<int>((sender, target, arg) => Assert.IsType<List<int>>(target).Add(arg * 10));
        var handler2 = new WeakEventHandler<int>((sender, target, arg) => Assert.IsType<List<int>>(target).Add(arg * 20));
        var handler3 = new WeakEventHandler<int>((sender, target, arg) => Assert.IsType<List<int>>(target).Add(arg * 30));
 
        e.AddHandler(target, handler1);
        e.AddHandler(target, handler2);
        e.AddHandler(target, handler3);
 
        e.RemoveHandler(target, handler2);
 
        e.RaiseEvent(sender, 1);
 
        AssertEx.Equal([10, 30], target);
        target.Clear();
 
        e.RemoveHandler(target, handler1);
        e.RemoveHandler(target, handler3);
 
        e.RaiseEvent(sender, 1);
        Assert.Empty(target);
    }
}