public void CurrentWeekWithCustomStartShouldReturnExpectedResult() { using ( ShimsContext.Create() ) { ShimDateTime.TodayGet = () => new DateTime( 2013, 6, 1 ); var expected = 23; var target = new GregorianCalendar(); var actual = target.CurrentWeek( DayOfWeek.Saturday ); Assert.Equal( expected, actual ); } }