Hi I am trying to use HUnit to test my Parsec-based parsers. I have the following code: import Text.ParserCombinators.Parsec import Test.HUnit test1 = TestCase $ assertEqual "msg" (Right '1') (parse digit "error" "1") Running it gives the following error: HUnitParsec.hs:5:19: No instance for (Eq ParseError) arising from a use of `assertEqual' at HUnitParsec.hs:(5,19)- (8,32) Possible fix: add an instance declaration for (Eq ParseError) In the second argument of `($)', namely `assertEqual "msg" (Right '1') (parse digit "error" "1")' In the expression: TestCase $ assertEqual "msg" (Right '1') (parse digit "error" "1") In the definition of `test1': test1 = TestCase $ assertEqual "msg" (Right '1') (parse digit "error" "1") Is the missing Eq instance intentional? What is the recommended way to use HUnit to test Parsec parsers? Bests, Manuel