megaparsec-5.0.0: old-tests/Bugs/Bug6.hs

module Bugs.Bug6 (main) where

import Text.Megaparsec
import Text.Megaparsec.String

import Test.Framework
import Test.Framework.Providers.HUnit
import Test.HUnit hiding (Test)

import Util

main :: Test
main =
  testCase "Look-ahead preserving error location (#6)" $
  parseErrors variable "return" @?= ["'return' is a reserved keyword"]

variable :: Parser String
variable = do
  x <- lookAhead (some letterChar)
  if x == "return"
    then fail "'return' is a reserved keyword"
    else string x