recipe_spec.rb

 let(:runner) do                                                                                                             
    memoized_runner('pd-gocd::agent') do |node|                                                                               
      #..... 
    end 
  end

spec_helper.rb

    def clear_runner(recipe)
      @@runners.delete recipe
    end

    def memoized_runner(recipe, options={}, &block)
      @@runners[recipe] ||= converged_runner(recipe, options, &block)
    end

    def converged_runner(recipe, options = {})
      runner = ChefSpec::SoloRunner.new(
        {file_cache_path: '/var/chef/cache'}.merge(options)
      )
      yield runner.node if block_given?
      runner.converge(recipe)
      runner
    end