gitlabhq/db/fixtures/development/008_merge_requests.rb

(1..300).each  do |i|
  # Random Project
  project_id = rand(2) + 1
  project = Project.find(project_id)

  # Random user
  user = project.users.sample
  user_id = user.id
  MergeRequestObserver.current_user = user

  MergeRequest.seed(:id, [{
    id: i,
    source_branch: 'master',
    target_branch: 'feature',
    project_id: project_id,
    author_id: user_id,
    assignee_id: user_id,
    closed: [true, false].sample,
    milestone: project.milestones.sample,
    title: Faker::Lorem.sentence(6)
  }])
end