Add a test for InputObject#prepare + loads

spec/graphql/schema/input_object_spec.rb

@@ -389,6 +389,18 @@ def resolve(input:)
         end
       end
 
+      class Thing < GraphQL::Schema::Object
+        field :name, String
+      end
+
+      class PrepareAndLoadInput < GraphQL::Schema::InputObject
+        argument :value, String
+        argument :thing_id, ID, loads: Thing
+        def prepare
+          { value: "Prepared: #{value}", thing: thing }
+        end
+      end
+
       class Query < GraphQL::Schema::Object
         field :inputs, String do
           argument :input, RangeInput
@@ -407,13 +419,35 @@ def inputs(input:)
         def prepare_once(input:)
           input.prepared_count
         end
+
+        field :prepare_and_load, String do
+          argument :input, PrepareAndLoadInput
+        end
+
+        def prepare_and_load(input:)
+          "#{input[:value]}/#{input[:thing][:name]}"
+        end
       end
 
       class Schema < GraphQL::Schema
         query(Query)
+
+        def self.resolve_type(_abs_t, _obj, _ctx)
+          Thing
+        end
+
+        def self.object_from_id(id, _ctx)
+          { name: "Thing #{id}"}
+        end
       end
     end
 
+    it "calls prepare and loads" do
+      query_str = "{ prepareAndLoad(input: { value: \"Hello\", thingId: \"123\"}) }"
+      res = InputObjectPrepareObjectTest::Schema.execute(query_str)
+      assert_equal "Prepared: Hello/Thing 123", res["data"]["prepareAndLoad"]
+    end
+
     it "calls prepare on the input object (literal)" do
       query_str = <<-GRAPHQL
       { inputs(input: { min: 5, max: 10 }) }