EffectiveAttribute.cs

using System;
using System.Globalization;
using NUnit.Framework;
using NUnit.Framework.Interfaces;
using NUnit.Framework.Internal;
using NUnit.Framework.Internal.Commands;

public sealed class EffectiveAttribute : NUnitAttribute, IWrapSetUpTearDown
{
    private readonly DateTime starting;

    public EffectiveAttribute(string starting)
    {
        this.starting = DateTime.Parse(starting, CultureInfo.InvariantCulture);
    }

    public TestCommand Wrap(TestCommand command)
    {
        return new Command(starting, command);
    }

    private sealed class Command : DelegatingTestCommand
    {
        private readonly DateTime starting;

        public Command(DateTime starting, TestCommand innerCommand)
            : base(innerCommand)
        {
            this.starting = starting;
        }

        public override TestResult Execute(TestExecutionContext context)
        {
            if (DateTime.Now < starting)
            {
                context.CurrentResult.RecordAssertion(
                    AssertionStatus.Inconclusive,
                    $"This test is not effective until {starting}.");

                context.CurrentResult.RecordTestCompletion();
                return context.CurrentResult;
            }

            context.CurrentResult.RecordAssertion(
                AssertionStatus.Error,
                $"Now that this test is effective, remove {nameof(EffectiveAttribute)} from the test method.");

            return innerCommand.Execute(context);
        }
    }
}