From: dot@dotat.at   
      
   Matthias-Christian Ott  wrote:   
   >   
   >If you have a formal (generative) grammar for your language, you can   
   >generate all valid strings of language and test whether your parser   
   >recognises them. So you have practical tests which also cover obscure   
   >programmes. You could use yagg [1] for this purpose.   
      
   As our esteemed moderator points out, you also want to test invalid   
   inputs. One possible tactic is to randomly perturb a valid program by   
   adding and/or deleting a few characters or tokens. (Though it might be   
   tricky to ensure you don't make an edit that leaves the program valid!)   
      
   Tony.   
   --   
   f.anthony.n.finch    http://dotat.at/   
   [I recall seeing some work about a decade ago on making small perturbations   
   to the source code of programs. -John]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)