Async transaction flow problem

AsyncTransactionFlow.cs

using System.Threading.Tasks;
using System.Transactions;
using NUnit.Framework;

[TestFixture]
public class TransactionFlowTest
{
    [Test]
    public void It_should_propagate_transaction_current_down_the_stack_sync()
    {
        Assert.IsNull(Transaction.Current);
        using (var scope = CreateScopeSync())
        {
            Assert.IsNotNull(scope);
            Assert.IsNotNull(Transaction.Current);
        }
        Assert.IsNull(Transaction.Current);
    }

    static TransactionScope CreateScopeSync()
    {
        return new TransactionScope(TransactionScopeOption.Required, new TransactionOptions());
    }

    [Test]
    public async Task It_should_propagate_transaction_current_down_the_stack_async()
    {
        Assert.IsNull(Transaction.Current);
        using (var scope = await CreateScopeAsync().ConfigureAwait(false))
        {
            Assert.IsNotNull(scope);
            Assert.IsNotNull(Transaction.Current);
        }
        Assert.IsNull(Transaction.Current);
    }

    static async Task<TransactionScope> CreateScopeAsync()
    {
        await Task.Yield();
        return new TransactionScope(TransactionScopeOption.Required, new TransactionOptions(), TransactionScopeAsyncFlowOption.Enabled);
    }
}