config_initializers_omniauth.rb

 Rails.application.config.middleware.use OmniAuth::Builder do
  provider :testing, Settings.oauth.testing.key, Settings.oauth.testing.secret
end

omniauth_testing.rb

module OmniAuth
  module Strategies
    class Testing
      include OmniAuth::Strategy
      
      option :name, :testing
      
      def request_phase; end
end

the error

Received wrong number of arguments. ["xxxx", "yyyyyyyyyy"]

Trace:
 # Make sure that all of the args have been dealt with, otherwise error out.
      fail(ArgumentError.new("Received wrong number of arguments. #{args.inspect}")) unless args.empty?

      yield options if block_given?
    end
    
    lib/omniauth/strategy.rb:in `initialize'