Validate fragment spread type existence

tests/Language/GraphQL/AST/EncoderSpec.hs

@@ -122,7 +122,7 @@ spec = do
     describe "definition" $
         it "indents block strings in arguments" $
             let arguments = [Argument "message" (String "line1\nline2")]
-                field = Field Nothing "field" arguments [] []
+                field = Field Nothing "field" arguments [] [] $ Location 0 0
                 operation = DefinitionOperation
                     $ SelectionSet (pure field)
                     $ Location 0 0

tests/Language/GraphQL/ValidateSpec.hs

@@ -300,7 +300,7 @@ spec =
                     }
              in validate queryString `shouldBe` Seq.singleton expected
 
-        it "rejects the fragment spread without a target" $
+        it "rejects fragment spreads without an unknown target type" $
             let queryString = [r|
               {
                 dog {
@@ -319,3 +319,20 @@ spec =
                     , path = []
                     }
              in validate queryString `shouldBe` Seq.singleton expected
+
+        it "rejects inline fragments without a target" $
+            let queryString = [r|
+              {
+                ... on NotInSchema {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Inline fragment is specified on type \"NotInSchema\" \
+                        \which doesn't exist in the schema."
+                    , locations = [AST.Location 3 17]
+                    , path = []
+                    }
+             in validate queryString `shouldBe` Seq.singleton expected