Type extensions objects can be empty

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- Bug Fix: [Object type extensions may be empty](https://github.com/absinthe-graphql/absinthe/pull/1228)
+
 ## 1.7.1
 - Breaking Bugfix: [Validate repeatable directives on schemas](https://github.com/absinthe-graphql/absinthe/pull/1179)
 - Breaking Bugfix: [Add "Objects must define fields" schema validation](https://github.com/absinthe-graphql/absinthe/pull/1167)

lib/absinthe/phase/schema/validation/object_must_define_fields.ex

@@ -18,6 +18,10 @@ defmodule Absinthe.Phase.Schema.Validation.ObjectMustDefineFields do
     obj
   end
 
+  defp validate_objects(%Blueprint.Schema.TypeExtensionDefinition{} = node) do
+    {:halt, node}
+  end
+
   defp validate_objects(%struct{} = node)
        when struct in [
               Blueprint.Schema.ObjectTypeDefinition,

test/absinthe/schema/rule/object_must_define_fields_test.exs

@@ -121,4 +121,24 @@ defmodule Absinthe.Schema.Rule.ObjectMustDefineFieldsTest do
       Code.eval_string(@schema)
     end)
   end
+
+  @schema ~S(
+    defmodule ExtendObjectSchema do
+      use Absinthe.Schema
+
+      query do
+        field :foo, :string
+      end
+
+      object :bar do
+        field :baz, :string
+      end
+
+      extend object :bar do
+      end
+    end
+    )
+  test "does not error on empty object extension" do
+    assert Code.eval_string(@schema)
+  end
 end