public void CurrentLastDayOfWeekInMonthShouldReturnExpectedResult() { using ( ShimsContext.Create() ) { ShimDateTime.TodayGet = () => new DateTime( 2013, 6, 1 ); var expected = new DateTime( 2013, 6, 28 ); var target = new GregorianCalendar(); var actual = target.CurrentLastDayOfWeekInMonth( DayOfWeek.Friday ); Assert.Equal( expected.Date, actual.Date ); } }