pyrites/haskell-experiments/test/Test/SimpleParserSpec.hs

{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE OverloadedRecordDot #-}
{-# HLINT ignore "Use const" #-}
{-# HLINT ignore "Unused LANGUAGE pragma" #-}
{-# HLINT ignore "Avoid lambda" #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE NoFieldSelectors #-}
{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}
{-# LANGUAGE TypeApplications #-}

module Test.SimpleParserSpec where

import Test.Hspec
import Text.Megaparsec
import SimpleParser

checkParse :: String -> Expr -> Expectation
checkParse text expectedExpr = 
  parse parseExpr "" text `shouldBe` Right expectedExpr

checkEval :: String -> Int -> Expectation
checkEval text expectedVal = 
  fmap eval (parse parseExpr "" text) `shouldBe` Right expectedVal


spec :: Spec
spec = do
  describe "evaluate expressions" $ do
    it "arithmetic on literals" $ do
      eval (BinaryExpr Add (Literal 2) (Literal 3) ) `shouldBe` 5
      eval (BinaryExpr Subtract (Literal 2) (Literal 3) ) `shouldBe` -1
      eval (BinaryExpr Multiply (Literal 2) (Literal 3) ) `shouldBe` 6
      eval (BinaryExpr Divide (Literal 7) (Literal 3) ) `shouldBe` 2
      eval (UnaryExpr Negate (Literal 7) ) `shouldBe` -7
    it "more complex arithmetic on literals" $ do
      eval (BinaryExpr Add 
        (UnaryExpr Negate (Literal 1)) 
        (BinaryExpr Divide (Literal 7) (Literal 3))
        ) `shouldBe` 1
    it "can parse basic expressions" $ do
      checkParse "2" (Literal 2)
      checkParse "2+3" (BinaryExpr Add (Literal 2) (Literal 3))
      checkParse "2+3+5" (BinaryExpr Add (BinaryExpr Add (Literal 2) (Literal 3)) (Literal 5))
      checkParse "2+3*5" (BinaryExpr Add (Literal 2) (BinaryExpr Multiply (Literal 3) (Literal 5)))
      checkParse "(2+3)*5" (BinaryExpr Multiply (BinaryExpr Add (Literal 2) (Literal 3)) (Literal 5) )
      checkParse "((2+3))*5" (BinaryExpr Multiply (BinaryExpr Add (Literal 2) (Literal 3)) (Literal 5) )
    it "can evaluate expressions correctly" $ do
      checkEval "2" 2
      checkEval "3*4/2" 6
      checkEval "2+3*6" 20
      checkEval "1-2+3" (-4)