Figure if a resource exists or not in Chef before notifying it

check_resource.rb

resource_not_found = {}
begin
  resources('ruby_block[my-resource-supposed-to-exist]')
rescue Chef::Exceptions::ResourceNotFound
  resource_not_found['ruby_block[my-resource-supposed-to-exist]'] = true
end

template '/etc/my/template.conf' do
  source 'template.conf.erb'
  mode '640'
  notifies :run, 'ruby_block[my-resource-supposed-to-exist]' unless resource_not_found['ruby_block[my-resource-supposed-to-exist]']
end