elm/exercises/strain/StrainTests.elm

module Main exposing (..)

import ElmTest exposing (..)
import Strain exposing (keep, discard)
import String


even : Int -> Bool
even number =
    number % 2 == 0


odd : Int -> Bool
odd number =
    number % 2 == 1


isFirstLetter : String -> String -> Bool
isFirstLetter letter word =
    (String.left 1 word) == letter


lessThanTen : number -> Bool
lessThanTen num =
    num < 10


tests : Test
tests =
    suite "Strain"
        [ test "empty keep"
            (assertEqual []
                (keep lessThanTen [])
            )
        , test "keep everything"
            (assertEqual [ 1, 2, 3 ]
                (keep lessThanTen [ 1, 2, 3 ])
            )
        , test "keep first and last"
            (assertEqual [ 1, 3 ]
                (keep odd [ 1, 2, 3 ])
            )
        , test "keep nothing"
            (assertEqual []
                (keep even [ 1, 3, 5, 7 ])
            )
        , test "keep neither first nor last"
            (assertEqual [ 2 ]
                (keep even [ 1, 2, 3 ])
            )
        , test "keep strings"
            (assertEqual [ "zebra", "zombies", "zealot" ]
                (keep (isFirstLetter "z") [ "apple", "zebra", "banana", "zombies", "cherimoya", "zealot" ])
            )
        , test "empty discard"
            (assertEqual []
                (discard lessThanTen [])
            )
        , test "discard everything"
            (assertEqual []
                (discard lessThanTen [ 1, 2, 3 ])
            )
        , test "discard first and last"
            (assertEqual [ 2 ]
                (discard odd [ 1, 2, 3 ])
            )
        , test "discard nothing"
            (assertEqual [ 1, 3, 5, 7 ]
                (discard even [ 1, 3, 5, 7 ])
            )
        , test "discard neither first nor last"
            (assertEqual [ 1, 3 ]
                (discard even [ 1, 2, 3 ])
            )
        , test "discard strings"
            (assertEqual [ "apple", "banana", "cherimoya" ]
                (discard (isFirstLetter "z") [ "apple", "zebra", "banana", "zombies", "cherimoya", "zealot" ])
            )
        ]


main : Program Never
main =
    runSuite tests