Add a test for gmsGet/Put

Language/Haskell/GhcMod/Monad.hs

@@ -23,6 +23,8 @@ module Language.Haskell.GhcMod.Monad (
   -- ** Conversion
   , toGhcModT
   -- ** Accessing 'GhcModEnv' and 'GhcModState'
+  , gmsGet
+  , gmsPut
   , options
   , cradle
   , getCompilerMode

test/MonadSpec.hs

@@ -25,3 +25,8 @@ spec = do
     describe "runGhcModT" $
         it "complains if the cabal file fails to parse while a sandbox is present" $ withDirectory_ "test/data/broken-cabal" $ do
           shouldReturnError $ runD' (gmCradle <$> ask)
+
+    describe "gmsGet/Put" $
+        it "work" $ do
+          (runD $ gmsPut (GhcModState Intelligent) >> gmsGet)
+            `shouldReturn` (GhcModState Intelligent)