# File test/test_queue.rb, line 19
    def test_push_pop_multi_thread
      spin_lock = true
      Thread.new{
        while (spin_lock)
          # locked.
        end
        @queue.push(PseudoIO.new)
      }
      Thread.new{
        while (spin_lock)
          # locked.
        end
        @queue.push(PseudoIO.new)
      }
      Thread.new{
        while (spin_lock)
          # locked.
        end
        @queue.push(PseudoIO.new)
      }
      Thread.new{
        while (spin_lock)
          # locked.
        end
        @queue.push(PseudoIO.new)
      }

      spin_lock = false
      assert_instance_of(PseudoIO, @queue.pop)
      assert_instance_of(PseudoIO, @queue.pop)
      assert_instance_of(PseudoIO, @queue.pop)
      assert_instance_of(PseudoIO, @queue.pop)
    end