You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test_sleep.rb
    path of file: ./repos/artichoke/artichoke-backend/vendor/ruby/test/fiber
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
require 'test/unit'
require_relative 'scheduler'

class TestFiberSleep < Test::Unit::TestCase
  ITEMS = [0, 1, 2, 3, 4]

  def test_sleep
    items = []

    thread = Thread.new do
      sched
    
  def test_sleep_returns_seconds_slept
    seconds = nil

    thread = Thread.new do
      scheduler = Scheduler.new
      Fiber.set_scheduler scheduler
      Fiber.schedule do
        seconds = sleep(2)
      end
    end

    thread.join

    assert_operator seconds, :>=, 2, "actual: %p" % seconds
  end