title: Should an exception be thrown and handled if it cannot happen?
body: <p>I have a function that takes three parameters (day, month &amp; year) and creates a new dateTime. It's a public function that gets called when any of three comboboxes are dropped down. </p>
  
  <p>When unit testing I accidentally entered an invalid value and it threw a invalid date time exception, but this won't be possible in the application as the comboboxes are pre-populated with valid values only.</p>
  
  <p>So question is should I still check and handle this exception in the function?</p>