using System;

using System.Runtime.CompilerServices;

using System.Threading;

using System.Threading.Tasks;

​

using NUnit.Framework;

​

[TestFixture]

public class ExecutionContextFlowTests

{

    private class TestSynchronizationContext : SynchronizationContext

    {

        /// <inheritdoc />

        public override SynchronizationContext CreateCopy()

        {

            return new TestSynchronizationContext();

        }

​

        /// <inheritdoc />

        public override bool Equals(object obj)

        {

            return obj is TestSynchronizationContext;

        }

​

        /// <inheritdoc />

        public override int GetHashCode()

        {

            return 0;

        }

    }

​

    [Test]

    public async Task Test()

    {

        /* Arrange */

​

        var syncCtx = new TestSynchronizationContext();

​

        Task<ExecutionContext> t;

        using (ExecutionContext.SuppressFlow())

        {

            t = Task.Run(() =>

            {

                SynchronizationContext prevCtx = SynchronizationContext.Current;

                SynchronizationContext.SetSynchronizationContext(syncCtx);

                try

                {

                    return ExecutionContext.Capture();

                }

                finally

                {

                    SynchronizationContext.SetSynchronizationContext(prevCtx);

                }

            });

        }

​

        ExecutionContext capturedContext = await t.ConfigureAwait(false);

        Assert.That(capturedContext, Is.Not.Null);

        Assert.That(SynchronizationContext.Current, Is.Not.EqualTo(syncCtx));

​

        /* Act */

​

        var syncCtxBox = new StrongBox<SynchronizationContext>();

        ExecutionContext.Run(

            capturedContext,

            box => ((StrongBox<SynchronizationContext>)box).Value = SynchronizationContext.Current,

            syncCtxBox

        );

​

        Assert.That(syncCtxBox.Value, Is.EqualTo(syncCtx));

    }

}

​

​

public static class Program

{

    public static int Main()

    {

        try

        {

            new ExecutionContextFlowTests().Test().GetAwaiter().GetResult();

        }

        catch (Exception ex)

        {

            Console.WriteLine("Test failed: {0}", ex);

            return 1;

        }

​

        Console.WriteLine("Test passed");

        return 0;

    }

}