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: client_add_test.rb
    path of file: ./repos/memcached/test/unit
    
    the code of the file until where you have to start completion: require 'test_helper'

    
  def test_add_expiry
    cache.set key, @value, ttl: 1
    assert cache.get(key)

    sleep(1.02)
    assert_nil cache.get(key)
  end