非同期実行するジョブをテストする際に、テスト結果を検証するために同期実行したい場合。
supportを作成して同期実行する設定を行う。

spec/rails_helper.rb

RSpec.configure do |config|
  ...
  config.include ActiveJob::TestHelper
  ...

  # deliver_later の同期実行。
  # system/modelテストが対象。
  %i(system model).each do |type|
    config.when_first_matching_example_defined(type: type) do
      require 'support/perform_enqueued_jobs'
    end
  end
end

spec/support/perform_enqueued_jobs.rb

RSpec.configure do |config|
  config.before(:each, :perform_enqueued_jobs) do |example|
    @old_perform_enqueued_jobs = queue_adapter.perform_enqueued_jobs
    @old_perform_enqueued_at_jobs = queue_adapter.perform_enqueued_at_jobs
    queue_adapter.perform_enqueued_jobs = true
    queue_adapter.perform_enqueued_at_jobs = true
  end
  config.after(:each, :perform_enqueued_jobs) do |example|
    queue_adapter.perform_enqueued_jobs = @old_perform_enqueued_jobs
    queue_adapter.perform_enqueued_at_jobs = @old_perform_enqueued_at_jobs
  end
end

使い方は以下。

spec/models/my_model_spec.rb

RSpec.describe MyModel, type: :model do
...
  describe 'when hogehoge', :perform_enqueued_jobs do
  ...
  end
end

spec/systems/system_spec.rb

RSpec.describe MyModel, type: :system do
...
  describe 'when hogehoge', :perform_enqueued_jobs do
  ...
  end
end

参考