title: how can I change environment variables when running rspec for ruby?
body: <p>I have several ruby scripts and test them with rspec.</p>
  
  <p>I put my environments in a env.rb file (for now) so I can access them locally and in production put them in the config variables.</p>
  
  <p>But when I run rspec, I would like different environment variables.  Two use cases:</p>
  
  <ul>
  <li>I run Twilio, so I want to be able to change the SID used to their Test Credentials</li>
  <li>I store things in a database as a service, and want to have a separate test database</li>
  </ul>