Repro for ruby-grape#1355.

spec/grape/api/patch_method_helpers_spec.rb

@@ -0,0 +1,80 @@
+require 'spec_helper'
+
+describe Grape::API::Helpers do
+  module PatchHelpersSpec
+    class PatchPublic < Grape::API
+      format :json
+      version 'public-v1', using: :header, vendor: 'grape'
+
+      get do
+        { ok: 'public' }
+      end
+    end
+
+    module AuthMethods
+      def authenticate!
+      end
+    end
+
+    class PatchPrivate < Grape::API
+      format :json
+      version 'private-v1', using: :header, vendor: 'grape'
+
+      helpers AuthMethods
+
+      before do
+        authenticate!
+      end
+
+      get do
+        { ok: 'private' }
+      end
+    end
+
+    class Main < Grape::API
+      mount PatchPublic
+      mount PatchPrivate
+    end
+  end
+
+  def app
+    PatchHelpersSpec::Main
+  end
+
+  context 'default' do
+    it 'public' do
+      get '/', {}, 'HTTP_ACCEPT' => 'application/vnd.grape-public-v1+json'
+      expect(last_response.status).to eq 200
+      expect(last_response.body).to eq({ ok: 'public' }.to_json)
+    end
+
+    it 'private' do
+      get '/', {}, 'HTTP_ACCEPT' => 'application/vnd.grape-private-v1+json'
+      expect(last_response.status).to eq 200
+      expect(last_response.body).to eq({ ok: 'private' }.to_json)
+    end
+
+    it 'default' do
+      get '/'
+      expect(last_response.status).to eq 200
+      expect(last_response.body).to eq({ ok: 'public' }.to_json)
+    end
+  end
+
+  context 'patch' do
+    it 'public' do
+      patch '/', {}, 'HTTP_ACCEPT' => 'application/vnd.grape-public-v1+json'
+      expect(last_response.status).to eq 405
+    end
+
+    it 'private' do
+      patch '/', {}, 'HTTP_ACCEPT' => 'application/vnd.grape-private-v1+json'
+      expect(last_response.status).to eq 405
+    end
+
+    it 'default' do
+      patch '/'
+      expect(last_response.status).to eq 405
+    end
+  end
+end