megaparsec/tests/Error.hs
mrkkrp 45f449ddb2 prefer longest match in ‘mergeError’, fixes #23
Since ‘mergeError’ is only used to merge errors from alternative
branches of parsing, longest match should be preferred.
2015-08-24 01:45:12 +06:00

134 lines
5.3 KiB
Haskell

-- -*- Mode: Haskell; -*-
--
-- QuickCheck tests for Megaparsec's parse errors.
--
-- Copyright © 2015 Megaparsec contributors
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are
-- met:
--
-- * Redistributions of source code must retain the above copyright notice,
-- this list of conditions and the following disclaimer.
--
-- * Redistributions in binary form must reproduce the above copyright
-- notice, this list of conditions and the following disclaimer in the
-- documentation and/or other materials provided with the distribution.
--
-- This software is provided by the copyright holders "as is" and any
-- express or implied warranties, including, but not limited to, the implied
-- warranties of merchantability and fitness for a particular purpose are
-- disclaimed. In no event shall the copyright holders be liable for any
-- direct, indirect, incidental, special, exemplary, or consequential
-- damages (including, but not limited to, procurement of substitute goods
-- or services; loss of use, data, or profits; or business interruption)
-- however caused and on any theory of liability, whether in contract,
-- strict liability, or tort (including negligence or otherwise) arising in
-- any way out of the use of this software, even if advised of the
-- possibility of such damage.
{-# OPTIONS -fno-warn-orphans #-}
module Error (tests) where
import Data.Bool (bool)
import Data.List (isPrefixOf, isInfixOf)
import Test.Framework
import Test.Framework.Providers.QuickCheck2 (testProperty)
import Test.QuickCheck
import Pos ()
import Text.Megaparsec.Error
import Text.Megaparsec.Pos
tests :: Test
tests = testGroup "Parse errors"
[ testProperty "extracting message string" prop_messageString
, testProperty "creation of new error messages" prop_newErrorMessage
, testProperty "messages are always well-formed" prop_wellFormedMessages
, testProperty "copying of error positions" prop_parseErrorCopy
, testProperty "setting of error position" prop_setErrorPos
, testProperty "addition of error message" prop_addErrorMessage
, testProperty "setting of error message" prop_setErrorMessage
, testProperty "position of merged error" prop_mergeErrorPos
, testProperty "messages of merged error" prop_mergeErrorMsgs
, testProperty "position of error is visible" prop_visiblePos
, testProperty "message components are visible" prop_visibleMsgs ]
instance Arbitrary Message where
arbitrary = ($) <$> elements constructors <*> arbitrary
where constructors = [Unexpected, Expected, Message]
instance Arbitrary ParseError where
arbitrary = do
ms <- listOf arbitrary
pe <- oneof [ newErrorUnknown <$> arbitrary
, newErrorMessage <$> arbitrary <*> arbitrary ]
return $ foldr addErrorMessage pe ms
prop_messageString :: Message -> Bool
prop_messageString m@(Unexpected s) = s == messageString m
prop_messageString m@(Expected s) = s == messageString m
prop_messageString m@(Message s) = s == messageString m
prop_newErrorMessage :: Message -> SourcePos -> Bool
prop_newErrorMessage msg pos = added && errorPos new == pos
where new = newErrorMessage msg pos
added = errorMessages new == bool [msg] [] (badMessage msg)
prop_wellFormedMessages :: ParseError -> Bool
prop_wellFormedMessages err = wellFormed $ errorMessages err
prop_parseErrorCopy :: ParseError -> Bool
prop_parseErrorCopy err =
foldr addErrorMessage (newErrorUnknown pos) msgs == err
where pos = errorPos err
msgs = errorMessages err
prop_setErrorPos :: SourcePos -> ParseError -> Bool
prop_setErrorPos pos err =
errorPos new == pos && errorMessages new == errorMessages err
where new = setErrorPos pos err
prop_addErrorMessage :: Message -> ParseError -> Bool
prop_addErrorMessage msg err =
wellFormed msgs && (badMessage msg || added)
where new = addErrorMessage msg err
msgs = errorMessages new
added = msg `elem` msgs && not (errorIsUnknown new)
prop_setErrorMessage :: Message -> ParseError -> Bool
prop_setErrorMessage msg err =
wellFormed msgs && (badMessage msg || (added && unique))
where new = setErrorMessage msg err
msgs = errorMessages new
added = msg `elem` msgs && not (errorIsUnknown new)
unique = length (filter (== fromEnum msg) (fromEnum <$> msgs)) == 1
prop_mergeErrorPos :: ParseError -> ParseError -> Bool
prop_mergeErrorPos e1 e2 = errorPos (mergeError e1 e2) == max pos1 pos2
where pos1 = errorPos e1
pos2 = errorPos e2
prop_mergeErrorMsgs :: ParseError -> ParseError -> Bool
prop_mergeErrorMsgs e1 e2' = errorPos e1 /= errorPos e2 || wellFormed msgsm
where e2 = setErrorPos (errorPos e1) e2'
msgsm = errorMessages $ mergeError e1 e2
prop_visiblePos :: ParseError -> Bool
prop_visiblePos err = show (errorPos err) `isPrefixOf` show err
prop_visibleMsgs :: ParseError -> Bool
prop_visibleMsgs err = all (`isInfixOf` shown) (errorMessages err >>= f)
where shown = show err
f (Unexpected s) = ["unexpected", s]
f (Expected s) = ["expecting", s]
f (Message s) = [s]
-- | @iwellFormed xs@ checks that list @xs@ is sorted and contains no
-- duplicates and no empty messages.
wellFormed :: [Message] -> Bool
wellFormed xs = and (zipWith (<) xs (tail xs)) && not (any badMessage xs)