title: Rspec stubbing method for only specific arguments
body: <p>Is there a way to stub method for only specific arguments. Something like this</p>
  
  <pre><code>boss.stub(:fire!).with(employee1).and_return(true)
  </code></pre>
  
  <p>If any other employee is passed to <code>boss.fire!</code> method, I'll get <code>boss received unexpected message</code> error, but what I would really like is just to override the method for specific argument, and leave it be for all others. </p>
  
  <p>Any ideas how this can be done?</p>