coolstuff.fs

let getLastSundays year = 
    let lastSundays = Dictionary<int, int>()
    // find all lastsundays
    [for month in 1..12->
          [for day in System.DateTime.DaysInMonth(year,month).. -1.. 1->
               System.DateTime(year,month,day).DayOfWeek,(month,day)]
                     |> Seq.find (fun (dayOfWeek,_) -> dayOfWeek = System.DayOfWeek.Sunday) ] 
                        |> Seq.map (fun ((_,x)) -> x) |> Seq.iter lastSundays.Add
    lastSundays

[<TestClass>]
type UnitTest() = 
    [<TestMethod>]
    [<TestCategory("Unit")>]
    member x.TestDayLightSavingsIn2015() = 
         Assert.AreEqual(23, findHoursInNorwegianDay 2015 3 29)
         Assert.AreEqual(25, findHoursInNorwegianDay 2015 10 25)
         Assert.AreEqual(24, findHoursInNorwegianDay 2015 4 27)

    [<TestMethod>]
    [<TestCategory("Unit")>]
    member x.DayLightSavingsProperties() = 
            let datetest (date :System.DateTime) = 
                let lastSunday = (getLastSundays date.Year).[date.Month]
                if (date.Year < 1997) then 
                    true // summertime was really strange before and we don't need to cover the past
                else if (date.Month = 3 && date.DayOfWeek = DayOfWeek.Sunday && date.Day = lastSunday) then
                    23 = findHoursInNorwegianDay date.Year date.Month date.Day 
                else if (date.Month = 10 && date.DayOfWeek = DayOfWeek.Sunday && date.Day = lastSunday) then
                    25 = findHoursInNorwegianDay date.Year date.Month date.Day 
                else 
                    24 = findHoursInNorwegianDay date.Year date.Month date.Day 
            Check.One({Config.Quick with MaxTest = 10000}, datetest)