service_generator.rb

class ServiceGenerator < Rails::Generators::NamedBase
  source_root File.expand_path('../templates', __FILE__)

  def copy_service_file
    template "service.rb", "app/services/#{file_name}.rb"
  end

  def copy_service_spec_file
    template "service_spec.rb", "spec/services/#{file_name}_spec.rb"
  end
end

service_template.rb

class <%= class_name %>
  def initialize(*args)
  end

  def call
  end

  def self.call(*args)
    new(args).call
  end

  private_class_method :new
end