System.Threading.Tests.AsyncLocalTests.AsyncMethodNotifications C# (CSharp) Method

        public static async Task AsyncMethodNotifications()
        {
            //
            // Define thread-local and async-local values.  The async-local value uses its notification
            // to keep the thread-local value in sync with the async-local value.
            //
            ThreadLocal<int> tls = new ThreadLocal<int>();
            AsyncLocal<int> als = new AsyncLocal<int>(args =>
            {
                tls.Value = args.CurrentValue;
            });

            Assert.Equal(tls.Value, als.Value);

            als.Value = 1;
            Assert.Equal(tls.Value, als.Value);

            als.Value = 2;
            Assert.Equal(tls.Value, als.Value);

            await Run(async () =>
            {
                Assert.Equal(tls.Value, als.Value);
                Assert.Equal(als.Value, 2);

                als.Value = 3;
                Assert.Equal(tls.Value, als.Value);

                Task t = Run(async () =>
                {
                    Assert.Equal(tls.Value, als.Value);
                    Assert.Equal(als.Value, 3);

                    als.Value = 4;

                    Assert.Equal(tls.Value, als.Value);
                    Assert.Equal(als.Value, 4);

                    await Task.Run(() =>
                    {
                        Assert.Equal(tls.Value, als.Value);
                        Assert.Equal(als.Value, 4);

                        als.Value = 5;

                        Assert.Equal(tls.Value, als.Value);
                        Assert.Equal(als.Value, 5);
                    });

                    Assert.Equal(tls.Value, als.Value);
                    Assert.Equal(als.Value, 4);

                    als.Value = 6;

                    Assert.Equal(tls.Value, als.Value);
                    Assert.Equal(als.Value, 6);
                });

                Assert.Equal(tls.Value, als.Value);
                Assert.Equal(als.Value, 3);

                await Task.Yield();

                Assert.Equal(tls.Value, als.Value);
                Assert.Equal(als.Value, 3);

                await t;

                Assert.Equal(tls.Value, als.Value);
                Assert.Equal(als.Value, 3);
            });

            Assert.Equal(tls.Value, als.Value);
            Assert.Equal(als.Value, 2);
        }