{-# LANGUAGE OverloadedStrings #-}

{-# LANGUAGE ScopedTypeVariables #-}

module ErrorMessages

  (

    tests

  ) where

import Prelude ()

import Prelude.Compat

import Data.Aeson (FromJSON(..), eitherDecode)

import Data.Proxy (Proxy(..))

import Instances ()

import Numeric.Natural (Natural)

import Test.Framework (Test)

import Test.Framework.Providers.HUnit (testCase)

import Test.HUnit (Assertion, assertFailure, assertEqual)

import qualified Data.ByteString.Lazy.Char8 as L

import qualified Data.HashMap.Strict as HM

tests :: [Test]

tests =

    [

      testCase "Int" int

    , testCase "Integer" integer

    , testCase "Natural" natural

    , testCase "String" string

    , testCase "HashMap" hashMap

    ]

int :: Assertion

int = do

  let t = test (Proxy :: Proxy Int)

  t "\"\"" $ expected "Int" "String"

  t "[]" $ expected "Int" "Array"

  t "{}" $ expected "Int" "Object"

  t "null" $ expected "Int" "Null"

integer :: Assertion

integer = do

  let t = test (Proxy :: Proxy Integer)

  t "44.44" $ expected "Integer" "floating number 44.44"

natural :: Assertion

natural = do

  let t = test (Proxy :: Proxy Natural)

  t "44.44" $ expected "Natural" "floating number 44.44"

  t "-50" $ expected "Natural" "negative number -50"

string :: Assertion

string = do

  let t = test (Proxy :: Proxy String)

  t "1" $ expected "String" "Number"

  t "[]" $ expected "String" "Array"

  t "{}" $ expected "String" "Object"

  t "null" $ expected "String" "Null"

hashMap :: Assertion

hashMap = do

  let t = test (Proxy :: Proxy (HM.HashMap String Int))

  t "\"\"" $ expected "HashMap k v" "String"

  t "[]" $ expected "HashMap k v" "Array"

expected :: String -> String -> String

expected ex enc = "Error in $: expected " ++ ex ++ ", encountered " ++ enc

test :: forall a proxy . (FromJSON a, Show a) => proxy a -> L.ByteString -> String -> Assertion

test _ v msg = case eitherDecode v of

    Left e -> assertEqual "Invalid error message" msg e

    Right (x :: a) -> assertFailure $ "Expected parsing to fail but it suceeded with: " ++ show x