# File lib/nanoc/extra/checking/runner.rb, line 111
    def run_checks(classes)
      return [] if classes.empty?

      checks = []
      issues = Set.new
      length = classes.map { |c| c.identifier.to_s.length }.max + 18
      classes.each do |klass|
        print format("  %-#{length}s", "Running #{klass.identifier} check… ")

        check = klass.new(@site)
        check.run

        checks << check
        issues.merge(check.issues)

        # TODO report progress

        puts check.issues.empty? ? 'ok'.green : 'error'.red
      end
      issues
    end