ActiveSupport::LogSubscriber::TestHelper::MockLogger

Let we have a module like below:

  module MyModule
    class << self
      def logger
        @logger ||= Logger.new(File.join(Rails.root, "log", "my_gem_#{Rails.env}.log"))
      end
    end
  end

To use this logger just type:

  MyModule.logger.info "This is a log line"

To stub in tests use (for rspec): require 'active_support/log_subscriber/test_helper'

  RSpec.configure do |config|
     config.include ActiveSupport::LogSubscriber::TestHelper

     config.before do
        MyModule.stub!(:logger).and_return(MockLogger.new)
     end
  end

Usefull in testing when you don't like to log anything.