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_gem_package.rb
    path of file: ./repos/ruby-packer/ruby/test/rubygems
    
    the code of the file until where you have to start completion: # coding: utf-8
# frozen_string_literal: true

require 'rubygems/package/tar_test_case'
require 'digest'

class TestGemPackage < Gem::Package::TarTestCase

  def setup
    super

    @spec = quick_gem 'a' do |s|
      s.description = 'Ï€'
      s.files = %w[lib/code.rb]
    end

    util_build_gem @s
    
  def test_build_time_source_date_epoch_automatically_set
    epoch = ENV["SOURCE_DATE_EPOCH"]
    ENV["SOURCE_DATE_EPOCH"] = nil

    start_time = Time.now.utc.to_i

    spec = Gem::Specification.new 'build', '1'
    spec.summary = 'build'
    spec.authors = 'build'
    spec.files = ['lib/code.rb']
    spec.rubygems_version = Gem::Version.new '0'

    package = Gem::Package.new spec.file_name

    end_time = Time.now.utc.to_i

    assert_kind_of Time, package.build_time

    build_time = package.build_time.to_i

    assert_operator(start_time, :<=, build_time)
    assert_operator(build_time, :<=, end_time)
  ensure
    ENV["SOURCE_DATE_EPOCH"] = epoch
  end