gistfile1.fs

namespace FsCheck.Ext

module Test =
    open System
    open FsCheck
    open FsCheck.Arb

    type JapaneseChar = char
     
    let japaneseChar (s: string) =
        let jc: JapaneseChar = char s
        jc
        
    type MyGenerators =
        static member JapaneseChar() =
            { new Arbitrary<JapaneseChar>() with
                override x.Generator = Gen.oneof [
                                        Gen.choose(0x3000, 0x303f) |> Gen.map (Char.ConvertFromUtf32 >> japaneseChar)
                                        Gen.choose(0x3040, 0x309f) |> Gen.map (Char.ConvertFromUtf32 >> japaneseChar)
                                        Gen.choose(0x30a0, 0x30ff) |> Gen.map (Char.ConvertFromUtf32 >> japaneseChar)
                                        Gen.choose(0xff00, 0xffef) |> Gen.map (Char.ConvertFromUtf32 >> japaneseChar)
                                        Gen.choose(0x4e00, 0x9faf) |> Gen.map (Char.ConvertFromUtf32 >> japaneseChar)
                                        Gen.choose(0x3400, 0x4dbf) |> Gen.map (Char.ConvertFromUtf32 >> japaneseChar)
                                        ]
                override x.Shrinker c =
                    seq { for c' in ['a';'b';'c'] do if c' < c || not (Char.IsLower c) then yield c' }
            }
     
    Arb.register<MyGenerators>() |> ignore
    let sample n = Gen.sample 1000 n
    
    type Target() =
        static member JapaneseChar (value:JapaneseChar) =
            (generate<JapaneseChar> |> sample 10 |> List.forall (fun _ -> true)
            , shrink<JapaneseChar> value |> Seq.forall (fun shrunkv -> int shrunkv <= abs (int value)))
     
    Check.QuickAll<Target>()

gistfile2.txt

--- Checking Target ---
Target.JapaneseChar-Ok, passed 100 tests.