title: Run rails Rake: test in Parallel (on multiple cores / speeding it up) using Miniest
body: <p>So running rake test (they are MiniTests) takes about 10 minutes for me (large rails project 95,000 lines of code in the /app directory). Its averaging about 25 assertions a second. The problem is there are a lot of tests. </p>
  
  <p>Is there a way to run these in parallel (They are MiniTests)? I noticed only 1 core seems to be doing the work. Whats the best practice to execute these in Parallel? </p>
  
  <p>mind you I am trying to best use all the resources (4-12 cores on the current machine the tests are running on). running them on separate machines isnt something i am looking at exploring currently. </p>
  
  <p>so its impossible to concurrently run code on 2 cores at the same time with MRI i take it? using Jruby isnt an option currently. </p>