title: How do I test that an std::error_code is not an error?
body: <p>I have a method that returns an <code>std::error_code</code>. I am not particularly interested in the error message, only in whether or not the method succeeded. </p>
  
  <p>What is the best way to test that an <code>std::error_code</code> represents a successful operation?</p>