DirectionTest.elm

module DecoderTests exposing (..)

import Test exposing (..)
import Expect
import Fuzz
import String
import Json.Decode exposing (..)
import Json.Decode.Extra exposing ((|:))
import Result
type Direction = North | South | East | West


stringToDirection : String -> Decoder Direction
stringToDirection str =
    case str of
        "North" -> succeed North
        "South" ->  succeed South
        "East"  ->  succeed East
        "West"  ->  succeed West
        _       -> fail ("Value " ++ str ++ "Is not a direction")

decodeDirection : Decoder Direction
decodeDirection = string|> andThen stringToDirection

all : Test
all =
    describe "Decode Direction"
        [
         test "North" <|
              \() ->
            Expect.equal (Result.Ok North) <| decodeString decodeDirection  "\"North\""
        , test "South" <|
              \() ->
            Expect.equal (Result.Ok South) <| decodeString decodeDirection  "\"South\""
        , test "East" <|
              \() ->
            Expect.equal (Result.Ok East) <| decodeString decodeDirection  "\"East\""
        , test "West" <|
              \() ->
            Expect.equal (Result.Ok West) <| decodeString decodeDirection  "\"West\""
        , test "No Direction" <|
              \() ->
            Expect.equal Nothing <| Result.toMaybe<| decodeString decodeDirection  "\"xxxx\""
        ]