title: Dead code detection in PHP
body: <p>I have a project with very messy code - lots of duplication and dead code here and there.</p>
  
  <p>Some time ago there was zero code coverage by unit-tests but now we're trying to write all new code in T.D.D. manner and lowering technical debt by covering "old" code by unit-tests as well(test-last technique).</p>
  
  <p><b>Business logic's complexity is quite high</b> and sometimes no one can answer whether some methods are used or not.</p>
  
  <p>How this dead code methods can be found? Extensive logging? Higher test coverage?(It is not very easy because customers want new features to come out)</p>