Parse interfaces implementing interfaces

tests/Language/GraphQL/AST/EncoderSpec.hs

@@ -181,7 +181,7 @@ spec = do
                 argument = Full.InputValueDefinition mempty "arg" someType Nothing mempty
                 arguments = Full.ArgumentsDefinition [argument]
                 definition' = Full.TypeDefinition
-                    $ Full.InterfaceTypeDefinition mempty "UUID" mempty
+                    $ Full.InterfaceTypeDefinition mempty "UUID" (Full.ImplementsInterfaces []) mempty
                     $ pure
                     $ Full.FieldDefinition mempty "value" arguments someType mempty
                 expected = "interface UUID {\n\

tests/Language/GraphQL/AST/ParserSpec.hs

@@ -103,6 +103,12 @@ spec = describe "Parser" $ do
             \  name: String\n\
             \}"
 
+    it "parses ImplementsInterfaces on interfaces" $
+        parse document "" `shouldSucceedOn`
+            "interface Person implements NamedEntity & ValuedEntity {\n\
+            \  name: String\n\
+            \}"
+
     it "parses minimal enum type definition" $
         parse document "" `shouldSucceedOn`
             "enum Direction {\n\