Merge pull request #1727 from jkowens/fix-1683

Fix infinite loop when mounting endpoint with same superclass

Author: dblock

.rubocop_todo.yml

@@ -34,7 +34,7 @@ Metrics/AbcSize:
 # Offense count: 282
 # Configuration parameters: CountComments, ExcludedMethods.
 Metrics/BlockLength:
-  Max: 3117
+  Max: 3125
 
 # Offense count: 9
 # Configuration parameters: CountComments.

CHANGELOG.md

@@ -14,6 +14,7 @@
 * [#1724](https://github.com/ruby-grape/grape/pull/1724): Optional nested array validation - [@ericproulx](https://github.com/ericproulx).
 * [#1725](https://github.com/ruby-grape/grape/pull/1725): Fix `rescue_from :all` documentation - [@Jelkster](https://github.com/Jelkster).
 * [#1726](https://github.com/ruby-grape/grape/pull/1726): Improved startup performance during API method generation - [@jkowens](https://github.com/jkowens).
+* [#1727](https://github.com/ruby-grape/grape/pull/1727): Fix infinite loop when mounting endpoint with same superclass - [@jkowens](https://github.com/jkowens).
 * Your contribution here.
 
 ### 1.0.1 (9/8/2017)

lib/grape/dsl/settings.rb

@@ -165,13 +165,13 @@ def within_namespace(&_block)
 
       private
 
-      # Builds the current class :inheritable_setting. If available, it returns the superclass's :inheritable_setting.
-      # Otherwise, a clean :inheritable_setting is returned.
+      # Builds the current class :inheritable_setting. If available, it inherits from
+      # the superclass's :inheritable_setting.
       def build_top_level_setting
-        if defined?(superclass) && superclass.respond_to?(:inheritable_setting) && superclass != Grape::API
-          superclass.inheritable_setting
-        else
-          Grape::Util::InheritableSetting.new
+        Grape::Util::InheritableSetting.new.tap do |setting|
+          if defined?(superclass) && superclass.respond_to?(:inheritable_setting) && superclass != Grape::API
+            setting.inherit_from superclass.inheritable_setting
+          end
         end
       end
     end

spec/grape/api_spec.rb

@@ -3129,6 +3129,16 @@ def static
         get '/two/v1/world'
         expect(last_response.status).to eq 200
       end
+
+      context 'when mounting class extends a subclass of Grape::API' do
+        it 'mounts APIs with the same superclass' do
+          base_api = Class.new(Grape::API)
+          a = Class.new(base_api)
+          b = Class.new(base_api)
+
+          expect { a.mount b }.to_not raise_error
+        end
+      end
     end
   end