using System;

using AutoFake;

var fake = new Fake<Calendar>();

var sut = fake.Rewrite(() => Calendar.Yesterday);

sut.Replace(() => DateTime.Now).Return(new DateTime(2016, 8, day: 8));

Console.WriteLine(sut.Execute());

​

public class Calendar

{

    public static DateTime Yesterday => DateTime.Now.AddDays(-1);

}