test_require_once.rb

require 'test/unit'
require 'tempfile'

class TestRequireOnce < Test::Unit::TestCase
  def test_require_fires_once_across_threads
    file = Tempfile.open(['target', '.rb'])
    file.puts "$foo += 1"
    file.close
    $foo = 0
    100.times do |idx|
      [1,2,3,4,5].map { |x|
        Thread.new {require file.path}
      }.each(&:join)
      raise "Concurrent requires caused double-loading: $foo = #{$foo} at #{idx}th try" if $foo != 1
      $foo = 0
      $".delete(file.path)
    end
  end
end

typescript

% rbx test_require_once.rb
Loaded suite test_require_once
Started
E
Finished in 0.041527 seconds.

  1) Error:
test_require_fires_once_across_threads(TestRequireOnce):
RuntimeError: Concurrent requires caused double-loading: $foo = 2 at 12th try
    test_require_once.rb:14:in `test_require_fires_once_across_threads'
    kernel/common/integer.rb:92:in `times'
    test_require_once.rb:10:in `test_require_fires_once_across_threads'
    kernel/bootstrap/array.rb:66:in `each'
    kernel/bootstrap/array.rb:66:in `each'

1 tests, 0 assertions, 0 failures, 1 errors
zsh: exit 1     /home/nahi/git/rubinius/bin/rbx test_require_once.rb