title: How to test if composer.lock is up to date?
body: <p>During development (multiple people in the team) sometimes <code>composer install</code> returns:</p>
  
  <p><strong>Warning: The lock file is not up to date with the latest changes in composer.json. You may be getting outdated dependencies. Run update to update them.</strong></p>
  
  <p>Is there a way to check for this very quickly (in milliseconds, without making any changes)?</p>
  
  <p>I understand how composer works. However when code merges in it doesn't necessarily cause merge conflicts on the <code>composer.json</code> or <code>composer.lock</code> file and it's not fun to run <code>composer install</code> all the time when theres almost never any changes and that command takes several minutes.</p>
  
  <p>If I'm able to quick test if the lock fail has fallen out of sync I can build it into the bash environment to notify every command. Similar to how people like their <code>git status</code> to be built into their bash prompt.</p>
  
  <p>Further more this makes sense in CI to make sure it does sneak it's way into the stable branch.</p>