-- | Shared test utilities.
module FWL.Util where

import Test.Tasty.HUnit
import Text.Parsec.String (Parser)
import Text.Parsec (parse)

import FWL.Parser (parseProgram)
import FWL.AST

-- | Assert a parser succeeds and return the result.
shouldParse :: (Show a) => Parser a -> String -> IO a
shouldParse p input =
  case parse p "<test>" input of
    Left err -> assertFailure ("Unexpected parse error:\n" ++ show err)
                >> undefined
    Right v  -> return v

-- | Assert a parser fails.
shouldFailParse :: (Show a) => Parser a -> String -> IO ()
shouldFailParse p input =
  case parse p "<test>" input of
    Left _  -> return ()
    Right v -> assertFailure ("Expected parse failure but got: " ++ show v)

-- | Parse a full program, asserting success.
parseOk :: String -> IO Program
parseOk src =
  case parseProgram "<test>" src of
    Left err -> assertFailure ("Parse error:\n" ++ show err) >> undefined
    Right p  -> return p

-- | Parse a full program, asserting failure.
parseFail :: String -> IO ()
parseFail src =
  case parseProgram "<test>" src of
    Left _  -> return ()
    Right p -> assertFailure ("Expected parse failure, got:\n" ++ show p)

-- | Extract the single declaration from a one-decl program.
singleDecl :: Program -> IO Decl
singleDecl (Program _ [d]) = return d
singleDecl (Program _ ds)  =
  assertFailure ("Expected 1 decl, got " ++ show (length ds)) >> undefined