Respect subscriptions in the executor

After the last commit there were a few places needed to be adjusted to
support subscriptions. This is done and a test case is added.

It is important to implement subscriptions now, because they require
changes to the library API, and they are a big missing part to finish
the executor. When the executor is finished, we can start to provide
more stable API without breaking everything every release. Validation
and introspection shouldn't require much changes to the API; AST would
require some changes to report good errors after the validation - this
is one thing I can think of.

Fixes #5.

5 files changed, 93 insertions, 32 deletions

diff --git a/tests/Language/GraphQL/ExecuteSpec.hs b/tests/Language/GraphQL/ExecuteSpec.hs
index f994482..7aab6c5 100644
--- a/tests/Language/GraphQL/ExecuteSpec.hs
+++ b/tests/Language/GraphQL/ExecuteSpec.hs
@@ -1,3 +1,7 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE OverloadedStrings #-}
 module Language.GraphQL.ExecuteSpec
     ( spec
@@ -5,6 +9,7 @@ module Language.GraphQL.ExecuteSpec
 
 import Data.Aeson ((.=))
 import qualified Data.Aeson as Aeson
+import Data.Conduit
 import Data.Either (fromRight)
 import Data.Functor.Identity (Identity(..))
 import Data.HashMap.Strict (HashMap)
@@ -15,11 +20,15 @@ import Language.GraphQL.Error
 import Language.GraphQL.Execute
 import Language.GraphQL.Type as Type
 import Language.GraphQL.Type.Out as Out
-import Test.Hspec (Spec, describe, it, shouldBe)
+import Test.Hspec (Spec, context, describe, it, shouldBe)
 import Text.Megaparsec (parse)
 
 schema :: Schema Identity
-schema = Schema {query = queryType, mutation = Nothing}
+schema = Schema
+    { query = queryType
+    , mutation = Nothing
+    , subscription = Just subscriptionType
+    }
 
 queryType :: Out.ObjectType Identity
 queryType = Out.ObjectType "Query" Nothing []
@@ -45,33 +54,66 @@ philosopherType = Out.ObjectType "Philosopher" Nothing []
         = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
     lastNameResolver = pure $ Type.String "Nietzsche"
 
+subscriptionType :: Out.ObjectType Identity
+subscriptionType = Out.ObjectType "Subscription" Nothing []
+    $ HashMap.singleton "newQuote"
+    $ EventStreamResolver quoteField (pure $ Type.Object mempty)
+    $ pure $ yield $ Type.Object mempty
+  where
+    quoteField =
+        Out.Field Nothing (Out.NonNullObjectType quoteType) HashMap.empty
+
+quoteType :: Out.ObjectType Identity
+quoteType = Out.ObjectType "Quote" Nothing []
+    $ HashMap.singleton "quote"
+    $ ValueResolver quoteField
+    $ pure "Naturam expelles furca, tamen usque recurret."
+  where
+    quoteField =
+        Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
+
 spec :: Spec
 spec =
     describe "execute" $ do
-        it "skips unknown fields" $
-            let data'' = Aeson.object
-                    [ "philosopher" .= Aeson.object
-                        [ "firstName" .= ("Friedrich" :: String)
+        context "Query" $ do
+            it "skips unknown fields" $
+                let data'' = Aeson.object
+                        [ "philosopher" .= Aeson.object
+                            [ "firstName" .= ("Friedrich" :: String)
+                            ]
+                        ]
+                    expected = Response data'' mempty
+                    execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
+                    actual = fromRight (singleError "")
+                        $ runIdentity
+                        $ either (pure . parseError) execute'
+                        $ parse document "" "{ philosopher { firstName surname } }"
+                in actual `shouldBe` expected
+            it "merges selections" $
+                let data'' = Aeson.object
+                        [ "philosopher" .= Aeson.object
+                            [ "firstName" .= ("Friedrich" :: String)
+                            , "lastName" .= ("Nietzsche" :: String)
+                            ]
                         ]
-                    ]
-                expected = Response data'' mempty
-                execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
-                actual = fromRight (singleError "")
-                    $ runIdentity
-                    $ either (pure . parseError) execute'
-                    $ parse document "" "{ philosopher { firstName surname } }"
-             in actual `shouldBe` expected
-        it "merges selections" $
-            let data'' = Aeson.object
-                    [ "philosopher" .= Aeson.object
-                        [ "firstName" .= ("Friedrich" :: String)
-                        , "lastName" .= ("Nietzsche" :: String)
+                    expected = Response data'' mempty
+                    execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
+                    actual = fromRight (singleError "")
+                        $ runIdentity
+                        $ either (pure . parseError) execute'
+                        $ parse document "" "{ philosopher { firstName } philosopher { lastName } }"
+                in actual `shouldBe` expected
+        context "Subscription" $
+            it "subscribes" $
+                let data'' = Aeson.object
+                        [ "newQuote" .= Aeson.object
+                            [ "quote" .= ("Naturam expelles furca, tamen usque recurret." :: String)
+                            ]
                         ]
-                    ]
-                expected = Response data'' mempty
-                execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
-                actual = fromRight (singleError "")
-                    $ runIdentity
-                    $ either (pure . parseError) execute'
-                    $ parse document "" "{ philosopher { firstName } philosopher { lastName } }"
-             in actual `shouldBe` expected
+                    expected = Response data'' mempty
+                    execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
+                    Left stream = runIdentity
+                        $ either (pure . parseError) execute'
+                        $ parse document "" "subscription { newQuote { quote } }"
+                    Just actual = runConduitPure $ stream .| await
+                in actual `shouldBe` expected
diff --git a/tests/Test/DirectiveSpec.hs b/tests/Test/DirectiveSpec.hs
index 4d31cb9..fb5c318 100644
--- a/tests/Test/DirectiveSpec.hs
+++ b/tests/Test/DirectiveSpec.hs
@@ -1,3 +1,7 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE QuasiQuotes #-}
 module Test.DirectiveSpec
@@ -14,7 +18,8 @@ import Test.Hspec (Spec, describe, it, shouldBe)
 import Text.RawString.QQ (r)
 
 experimentalResolver :: Schema IO
-experimentalResolver = Schema { query = queryType, mutation = Nothing }
+experimentalResolver = Schema
+    { query = queryType, mutation = Nothing, subscription = Nothing }
   where
     queryType = Out.ObjectType "Query" Nothing []
         $ HashMap.singleton "experimentalField"
diff --git a/tests/Test/FragmentSpec.hs b/tests/Test/FragmentSpec.hs
index af1812c..71d7e9a 100644
--- a/tests/Test/FragmentSpec.hs
+++ b/tests/Test/FragmentSpec.hs
@@ -1,3 +1,7 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE QuasiQuotes #-}
 module Test.FragmentSpec
@@ -76,7 +80,7 @@ sizeFieldType
 
 toSchema :: Text -> (Text, Value) -> Schema IO
 toSchema t (_, resolve) = Schema
-    { query = queryType, mutation = Nothing }
+    { query = queryType, mutation = Nothing, subscription = Nothing }
   where
     unionMember = if t == "Hat" then hatType else shirtType
     typeNameField = Out.Field Nothing (Out.NamedScalarType string) mempty
diff --git a/tests/Test/RootOperationSpec.hs b/tests/Test/RootOperationSpec.hs
index 7202104..621d496 100644
--- a/tests/Test/RootOperationSpec.hs
+++ b/tests/Test/RootOperationSpec.hs
@@ -1,3 +1,7 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE QuasiQuotes #-}
 module Test.RootOperationSpec
@@ -20,8 +24,10 @@ hatType = Out.ObjectType "Hat" Nothing []
 
 schema :: Schema IO
 schema = Schema
-    (Out.ObjectType "Query" Nothing [] hatFieldResolver)
-    (Just $ Out.ObjectType "Mutation" Nothing [] incrementFieldResolver)
+    { query = Out.ObjectType "Query" Nothing [] hatFieldResolver
+    , mutation = Just $ Out.ObjectType "Mutation" Nothing [] incrementFieldResolver
+    , subscription = Nothing
+    }
   where
     garment = pure $ Object $ HashMap.fromList
         [ ("circumference", Int 60)
diff --git a/tests/Test/StarWars/Schema.hs b/tests/Test/StarWars/Schema.hs
index ed3c32c..99200ff 100644
--- a/tests/Test/StarWars/Schema.hs
+++ b/tests/Test/StarWars/Schema.hs
@@ -20,7 +20,11 @@ import Prelude hiding (id)
 -- See https://github.com/graphql/graphql-js/blob/master/src/__tests__/starWarsSchema.js
 
 schema :: Schema Identity
-schema = Schema { query = queryType, mutation = Nothing }
+schema = Schema
+    { query = queryType
+    , mutation = Nothing
+    , subscription = Nothing
+    }
   where
     queryType = Out.ObjectType "Query" Nothing [] $ HashMap.fromList
         [ ("hero", heroFieldResolver)