title: Testing concurrent access on Rails 3 application
body: <p>This question is a follow up from this other question: <a href="https://stackoverflow.com/questions/7166342/rails-3-locking-tables-on-an-auction-type-engine">Rails 3, locking tables on an auction type engine</a></p>
  
  <p>I've implemented the solution using Pessimistic Locking directly on Rails 3. Now I want to write some tests that exercise my code. I have no idea how to test concurrency problems on Rails. Any hint or gem?</p>
  
  <p>The particular piece of code is very very critical and I want to be sure it is well tested. </p>