A nice small wrapper around DateTime. Makes it possible to override the returned DateTime, which is very handy in unit tests

SystemTime.cs

using System;
using System.Diagnostics.CodeAnalysis;

public class SystemTime
{
    [SuppressMessage("StyleCop.CSharp.MaintainabilityRules", "SA1401:FieldsMustBePrivate", Justification = "Reviewed. Suppression is OK here.")]
    public static Func<DateTime> Now = () => DateTime.Now;

    [SuppressMessage("StyleCop.CSharp.MaintainabilityRules", "SA1401:FieldsMustBePrivate", Justification = "Reviewed. Suppression is OK here.")]
    public static Func<DateTime> UtcNow = () => DateTime.UtcNow;
}