Merge pull request #141 from sunwukonga/issues/118/make-enum-resolver-monadic

Close #118. Make resolver for Enum monadic.

Author: jml

src/GraphQL/Resolver.hs

@@ -207,8 +207,8 @@ instance forall m hg. (Monad m, Applicative m, HasResolver m hg) => HasResolver
     map aggregateResults a
 
 instance forall m ksN enum. (Applicative m, API.GraphQLEnum enum) => HasResolver m (API.Enum ksN enum) where
-  type Handler m (API.Enum ksN enum) = enum
-  resolve handler Nothing = (pure . ok . GValue.ValueEnum . API.enumToValue) handler
+  type Handler m (API.Enum ksN enum) = m enum
+  resolve handler Nothing = map (ok . GValue.ValueEnum . API.enumToValue) handler
   resolve _ (Just ss) = throwE (SubSelectionOnLeaf ss)
 
 instance forall m hg. (HasResolver m hg, Monad m) => HasResolver m (Maybe hg) where

tests/EnumTests.hs

@@ -1,5 +1,5 @@
 {-# LANGUAGE DeriveGeneric #-}
-module EnumTests () where
+module EnumTests ( Mode(Directory, NormalFile, ExecutableFile, Symlink) ) where
 
 import Protolude hiding (Enum)
 

tests/ResolverTests.hs

@@ -17,6 +17,7 @@ import GraphQL.API
   ( Object
   , Field
   , Argument
+  , Enum
   , (:>)
   )
 import GraphQL.Resolver
@@ -26,6 +27,8 @@ import GraphQL.Resolver
   )
 import GraphQL.Internal.Output (singleError)
 
+import EnumTests ( Mode(NormalFile) )
+
 -- Test a custom error monad
 type TMonad = ExceptT Text IO
 type T = Object "T" '[] '[ Field "z" Int32
@@ -63,6 +66,13 @@ handler = pure $ \fooId -> do
   -- have to wrap the result in a pure.
   sequence $ fmap (pure . viewFoo) foo
 
+-- Enum test
+type EnumQuery = Object "File" '[]
+  '[ Field "mode" (Enum "modeEnumName" Mode) ]
+
+enumHandler :: Handler IO EnumQuery
+enumHandler = pure $ pure NormalFile
+-- /Enum test
 
 tests :: IO TestTree
 tests = testSpec "TypeAPI" $ do
@@ -80,3 +90,7 @@ tests = testSpec "TypeAPI" $ do
     it "Just works" $ do
       Success object <- interpretAnonymousQuery @Query handler "{ test(id: \"10\") { name } }"
       encode object `shouldBe` "{\"test\":{\"name\":\"Mort\"}}"
+  describe "Parse, validate and execute queries against API" $ do
+    it "API.Enum works" $ do
+      Success object <- interpretAnonymousQuery @EnumQuery enumHandler "{ mode }"
+      encode object `shouldBe` "{\"mode\":\"NormalFile\"}"