intervention.rb

class Intervention
  include Mongoid::Document

  belongs_to :drug_therapy_problem, :inverse_of => :interventions

  after_update :im_updated
  after_create :im_created
  after_save :im_saved

  private

  def im_updated
    puts "im_updated"
  end
  def im_created
    puts "im_created"
  end
  def im_saved
    puts "im_saved"
  end
end

intervention_spec.rb

it "should call update, create and save hooks" do 
 @patient = Patient.make(:full)
 @dtp = @patient.drug_therapy_problems.first
 intervention = @dtp.interventions.create(Intervention.make.attributes)
 intervention.save!
end

output.txt

im_saved im_created im_saved