title: Reliably testing NSDateFormatter/iOS's 12-hour format-rewriting behavior
body: <p><a href="https://stackoverflow.com/questions/6613110/what-is-the-best-way-to-deal-with-the-nsdateformatter-locale-feature">On iOS, NSDateFormatter has a “feature” where it rewrites your format string if the user has 12-hour time enabled.</a></p>
  
  <p>I can fix that easily enough (set the formatter's locale to <code>en_US_POSIX</code>); that's not the difficulty.</p>
  
  <p>My difficulty is that I want to create a test case that detects the 12-hour-rewriting behavior. I want to set things up so that when my formatter (which should only ever emit 24-hour date strings) spits out a 12-hour date string, at least one test case fails.</p>
  
  <p>I have an iOS test bundle set for SDK current (currently 6.1), target 5.0. When I run my tests under this target, all of my times are still 24-hour.</p>
  
  <p><a href="https://github.com/boredzo/iso-8601-date-formatter/issues/15" rel="nofollow noreferrer">I have at least one report of this occurring in the wild</a>, so all I need now is to reproduce it reliably in a test case.</p>