Lcm recipe, how to stub the not_if?

lcm.rb

powershell_script 'Configure the LCM' do
  code <<-EOH
  Configuration ConfigLCM
  {
    Node "localhost"
    {
      LocalConfigurationManager
      {
        ConfigurationMode = "ApplyOnly"
        RebootNodeIfNeeded = $false
      }
    }
  }
  ConfigLCM -OutputPath "#{Chef::Config[:file_cache_path]}\\DSC_LCM"
  Set-DscLocalConfigurationManager -Path "#{Chef::Config[:file_cache_path]}\\DSC_LCM"
  EOH
  not_if '(Get-DscLocalConfigurationManager |select -ExpandProperty "ConfigurationMode") -eq "ApplyOnly"'
end