Allow Capybara to walk hand in hand with freezed time

time_freezer.rb

# Due to Capybara's intolerance to tools that freeze time
# (specifically Time.now), we only freeze Time.current here
# @param time [Time] Time. But may be anything else if you like
# @example
#   TimeFreezer.freeze_current_time('lol') do
#     Time.current #=> lol
#     Time.now #=> Your system time
#   end
#   Time.current #=> Your time with respect to Time.zone
# 
# spec/rails_helper.rb
# RSpec.configure do |config|
#   config.include TimeFreezer
# end
#

module TimeFreezer
  extend ActiveSupport::Concern

  def freeze_current_time time
    freeze time
    yield
  ensure
    unfreeze
  end

  private

  def freeze time
    ActiveSupport::TimeZone.class_eval do
      alias_method :old_now, :now
    end
    ActiveSupport::TimeZone.send(:define_method, :now) { time }
  end

  def unfreeze
    ActiveSupport::TimeZone.class_eval do
      remove_method :now
      alias_method :now, :old_now
      remove_method :old_now
    end
  end
end