assert_queries - rails 4

assert_queries.rb

  # Assertion for checking the number of queries executed within the &block
  def assert_queries(num = 1, &block)
    queries  = []
    callback = lambda { |name, start, finish, id, payload|
      queries << payload[:sql] if payload[:sql] =~ /^SELECT|UPDATE|INSERT/
    }

    ActiveSupport::Notifications.subscribed(callback, "sql.active_record", &block)
  ensure
    assert_equal num, queries.size, "#{queries.size} instead of #{num} queries were executed.#{queries.size == 0 ? '' : "\nQueries:\n#{queries.join("\n")}"}"
  end