Re-added Grape::API::Helpers for backward compatibility, broken in #716.

lib/grape.rb

@@ -106,6 +106,10 @@ module DSL
     autoload :Routing,           'grape/dsl/routing'
     autoload :Validations,       'grape/dsl/validations'
   end
+
+  class API
+    autoload :Helpers,           'grape/api/helpers'
+  end
 end
 
 require 'grape/version'

lib/grape/api/helpers.rb

@@ -0,0 +1,7 @@
+module Grape
+  class API
+    module Helpers
+      include Grape::DSL::Helpers::BaseHelper
+    end
+  end
+end

spec/grape/api/helpers_spec.rb

@@ -0,0 +1,36 @@
+require 'spec_helper'
+
+describe Grape::API::Helpers do
+  module SharedParams
+    extend Grape::API::Helpers
+
+    params :pagination do
+      optional :page, type: Integer
+      optional :size, type: Integer
+    end
+  end
+
+  subject do
+    Class.new(Grape::API) do
+      helpers SharedParams
+      format :json
+
+      params do
+        use :pagination
+      end
+      get do
+        declared(params, include_missing: true)
+      end
+    end
+  end
+
+  def app
+    subject
+  end
+
+  it 'defines parameters' do
+    get '/'
+    expect(last_response.status).to eq 200
+    expect(last_response.body).to eq({ page: nil, size: nil }.to_json)
+  end
+end