Fix resolvers returning a list in the reverse order

CHANGELOG.md

@@ -11,6 +11,9 @@ and this project adheres to
 - Partial schema printing: schema definition encoder.
 - `Semigroup` and `Monoid` instances for `AST.Document.Description`.
 
+### Fixed
+- Fix resolvers returning a list in the reverse order.
+
 ## [1.1.0.0] - 2022-12-24
 ### Changed
 - Removed deprecated `Language.GraphQL.Error` functions: `addErr`, `addErrMsg`,

graphql.cabal

@@ -110,7 +110,7 @@ test-suite graphql-test
     conduit,
     exceptions,
     graphql,
-    hspec ^>= 2.9.1,
+    hspec ^>= 2.10.9,
     hspec-expectations ^>= 0.8.2,
     hspec-megaparsec ^>= 2.2.0,
     megaparsec,

src/Language/GraphQL/Execute.hs

@@ -39,6 +39,7 @@ import qualified Data.List.NonEmpty as NonEmpty
 import Data.Maybe (fromMaybe)
 import Data.Sequence (Seq)
 import qualified Data.Sequence as Seq
+import qualified Data.Vector as Vector
 import Data.Text (Text)
 import qualified Data.Text as Text
 import Data.Typeable (cast)
@@ -466,12 +467,12 @@ completeValue :: (MonadCatch m, Serialize a)
 completeValue (Out.isNonNullType -> False) _ _ Type.Null =
     pure null
 completeValue outputType@(Out.ListBaseType listType) fields errorPath (Type.List list)
-    = foldM go (0, []) list >>= coerceResult outputType . List . snd
+    = foldM go Vector.empty list >>= coerceResult outputType . List . Vector.toList
   where
-    go (index, accumulator) listItem = do
+    go accumulator listItem =
-        let updatedPath = Index index : errorPath
+        let updatedPath = Index (Vector.length accumulator) : errorPath
-        completedValue <- completeValue listType fields updatedPath listItem
+         in Vector.snoc accumulator
-        pure (index + 1, completedValue : accumulator)
+            <$> completeValue listType fields updatedPath listItem
 completeValue outputType@(Out.ScalarBaseType _) _ _ (Type.Int int) =
     coerceResult outputType $ Int int
 completeValue outputType@(Out.ScalarBaseType _) _ _ (Type.Boolean boolean) =

tests/Language/GraphQL/ExecuteSpec.hs

@@ -66,8 +66,9 @@ queryType :: Out.ObjectType IO
 queryType = Out.ObjectType "Query" Nothing []
     $ HashMap.fromList
     [ ("philosopher", ValueResolver philosopherField philosopherResolver)
-    , ("genres", ValueResolver genresField genresResolver)
+    , ("throwing", ValueResolver throwingField throwingResolver)
     , ("count", ValueResolver countField countResolver)
+    , ("sequence", ValueResolver sequenceField sequenceResolver)
     ]
   where
     philosopherField =
@@ -75,15 +76,22 @@ queryType = Out.ObjectType "Query" Nothing []
         $ HashMap.singleton "id"
         $ In.Argument Nothing (In.NamedScalarType id) Nothing
     philosopherResolver = pure $ Object mempty
-    genresField =
+    throwingField =
         let fieldType = Out.ListType $ Out.NonNullScalarType string
          in Out.Field Nothing fieldType HashMap.empty
-    genresResolver :: Resolve IO
+    throwingResolver :: Resolve IO
-    genresResolver = throwM PhilosopherException
+    throwingResolver = throwM PhilosopherException
     countField =
         let fieldType = Out.NonNullScalarType int
          in Out.Field Nothing fieldType HashMap.empty
     countResolver = pure ""
+    sequenceField =
+        let fieldType = Out.ListType $ Out.NonNullScalarType int
+         in Out.Field Nothing fieldType HashMap.empty
+    sequenceResolver = pure intSequence
+
+intSequence :: Value
+intSequence = Type.List [Type.Int 1, Type.Int 2, Type.Int 3]
 
 musicType :: Out.ObjectType IO
 musicType = Out.ObjectType "Music" Nothing []
@@ -344,14 +352,14 @@ spec =
                 in sourceQuery `shouldResolveTo` expected
 
             it "gives location information for failed result coercion" $
-                let data'' = Object $ HashMap.singleton "genres" Null
+                let data'' = Object $ HashMap.singleton "throwing" Null
                     executionErrors = pure $ Error
                         { message = "PhilosopherException"
                         , locations = [Location 1 3]
-                        , path = [Segment "genres"]
+                        , path = [Segment "throwing"]
                         }
                     expected = Response data'' executionErrors
-                    sourceQuery = "{ genres }"
+                    sourceQuery = "{ throwing }"
                 in sourceQuery `shouldResolveTo` expected
 
             it "sets data to null if a root field isn't nullable" $
@@ -375,6 +383,12 @@ spec =
                     sourceQuery = "{ philosopher(id: \"1\") { firstLanguage } }"
                 in sourceQuery `shouldResolveTo` expected
 
+            it "returns list elements in the original order" $
+                let data'' = Object $ HashMap.singleton "sequence" intSequence
+                    expected = Response data'' mempty
+                    sourceQuery = "{ sequence }"
+                in sourceQuery `shouldResolveTo` expected
+
             context "queryError" $ do
                 let namedQuery name = "query " <> name <> " { philosopher(id: \"1\") { interest } }"
                     twoQueries = namedQuery "A" <> " " <> namedQuery "B"