-- Copyright 2021 Google LLC
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
--      http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.

-- | Assertion functions for QuickCheck based on 'Diff'.

module Data.Portray.Diff.QuickCheck ((=-=)) where

import Test.QuickCheck (Property, counterexample)

import Data.Portray.Diff (Diff(..))
import Data.Portray.Pretty (prettyShowPortrayal)

-- | Same as ('Test.QuickCheck.==='), using 'Diff' to compare and report errors.
infix 4 =-=
(=-=) :: Diff a => a -> a -> Property
(=-=) a b = uncurry counterexample $ case diff a b of
  Nothing -> ("", True)
  Just d -> (prettyShowPortrayal d, False)