title: How do you setup multiple jest configs within a single project?
body: <p>In the <code>create-react-app</code> boilerplate it has both server and client code using the same <code>package.json</code> file.  I'd like to have three separate jest configs: client unit tests, server unit tests, and server integration tests.  Unfortunately, I haven't been able to get this to work.  My plan was to have <code>yarn run</code> commands for each option and then specify the config to jest using the <code>--config</code> CLI option.  But then I ran into <a href="https://github.com/facebook/jest/issues/3584" rel="noreferrer">this roadblock</a> which happens on both v20 and v21 and is showing no progress.   Basically, people are reporting issues with reading config files using <code>--config</code> and the fallback is to use the config <code>package.json</code>.  Unfortunately, you can only specify a single config file.</p>
  
  <p>Has anyone managed to get this to work and if so can you describe your setup (the version of jest, etc).  I'm wondering if I need to downgrade to v19.  Alternatively, am I just taking the wrong approach?</p>