gistfile1.txt

  3 describe Comment do
  4   it "fires an event when created" do
  5     expect { Comment.make! }.to fire_event :comment_left
  6   end
  7 end

...

 38 RSpec::Matchers.define :fire_event do |event_type|
 39   match do |actual|
 40     expect(&actual).to change{TimelineEvent.count}.by(1)
 41   end
 42 end