hls-tactics-plugin-1.0.0.0: test/AutoTupleSpec.hs

{-# OPTIONS_GHC -fno-warn-orphans #-}

module AutoTupleSpec where

import Data.Either (isRight)
import Ide.Plugin.Tactic.Judgements (mkFirstJudgement)
import Ide.Plugin.Tactic.Machinery
import Ide.Plugin.Tactic.Tactics (auto')
import Ide.Plugin.Tactic.Types
import OccName (mkVarOcc)
import Test.Hspec
import Test.QuickCheck
import Type (mkTyVarTy)
import TysPrim (alphaTyVars)
import TysWiredIn (mkBoxedTupleTy)


spec :: Spec
spec = describe "auto for tuple" $ do
  it "should always be able to discover an auto solution" $ do
    property $ do
      -- Pick some number of variables
      n <- choose (1, 7)
      let vars = fmap mkTyVarTy $ take n alphaTyVars
      -- Pick a random ordering
      in_vars  <- shuffle vars
      -- Randomly associate them into tuple types
      in_type  <- mkBoxedTupleTy
                . fmap mkBoxedTupleTy
              <$> randomGroups in_vars
      out_type <- mkBoxedTupleTy
                . fmap mkBoxedTupleTy
              <$> randomGroups vars
      pure $
          -- We should always be able to find a solution
          runTactic
            emptyContext
            (mkFirstJudgement
              (Hypothesis $ pure $ HyInfo (mkVarOcc "x") UserPrv $ CType in_type)
              True
              out_type)
            (auto' $ n * 2) `shouldSatisfy` isRight


randomGroups :: [a] -> Gen [[a]]
randomGroups [] = pure []
randomGroups as = do
  n <- choose (1, length as)
  (:) <$> pure (take n as)
      <*> randomGroups (drop n as)