code: function(opts) {
  		if (opts.preScriptFile) {
  			var path = require('path');
  			opts.preScript = require(path.resolve(opts.preScriptFile));
  			delete opts.preScriptFile;
  		}
  		opts.preScript = opts.preScript || function(browser) {
  			return;
  		};
  		return opts;
  	}
docs: preScript, preScriptFile