module ExprTests where

import Expr
import Test.HUnit

inner :: Expr
inner = Abs "x" (Var 0 "A") $ Var 2 "f" <.> Var 0 "x"

e1 :: Expr
e1 = Abs "A" Star inner

fFree :: Test
fFree = TestCase $ assertBool "f free" $ occursFree 0 e1

incE1 :: Test
incE1 =
    TestCase $
        assertEqual
            "incIndices e1"
            ( Abs "A" Star $
                Abs "x" (Var 0 "A") $
                    Var 3 "f" <.> Var 0 "x"
            )
            (incIndices e1)

after :: Expr
after = Abs "x" (Var 2 "B") $ Var 1 "f" <.> Var 0 "x"

substE1 :: Test
substE1 =
    TestCase $
        assertEqual
            "e1[A := B]"
            after
            (subst 0 (Var 2 "B") inner)

betaNFe1 :: Test
betaNFe1 =
    TestCase $
        assertEqual
            "e1 B"
            after
            (betaNF $ e1 <.> Var 2 "B")

tests :: Test
tests =
    TestList
        [ TestLabel "fFree" fFree
        , TestLabel "incE1" incE1
        , TestLabel "substE1" substE1
        , TestLabel "betaNFe1" betaNFe1
        ]