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_ext_configure_builder.rb
    path of file: ./repos/ruby/test/rubygems
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

require_relative "helper"
require "rubygems/ext"

class TestGemExtConfigureBuilder < Gem::TestCase
  def setup
    super

    @makefile_body =
      "clean:\n\t@echo ok\nall:\n\t@echo ok\ninstall:\n\t@echo ok"

    @ext = 
    
  def test_self_build_fail
    pend("test_self_build_fail skipped on MS Windows (VC++)") if vc_windows?
    output = []

    error = assert_raise Gem::InstallError do
      Gem::Ext::ConfigureBuilder.build nil, @dest_path, output, [], nil, @ext
    end

    shell_error_msg = %r{(\./configure: .*)|((?:[Cc]an't|cannot) open '?\./configure'?(?:: No such file or directory)?)}
    sh_prefix_configure = "sh ./configure --prefix\\="

    assert_match "configure failed", error.message

    assert_match(/^current directory:/, output.shift)
    assert_equal "#{sh_prefix_configure}#{@dest_path}", output.shift
    assert_match(/#{shell_error_msg}/, output.shift)
    assert_equal true, output.empty?
  end