code: function specFilter(pattern, files) {
          var specPattern,
              patternArray,
              filteredArray = [],
              scriptSpecs = [],
              matchPath = function (path) {
                  return Boolean(path.match(specPattern));
              };
  
          if (pattern) {
              // For '*' to work as a wildcard.
              pattern = pattern.split('*').join('[\\S]*').replace(/\./g, '\\.');
              // This allows for comma separated strings to which we can match the
              // spec files.
              patternArray = pattern.split(',');
  
              while (patternArray.length > 0) {
                  pattern = (patternArray.splice(0, 1)[0]);
                  if (pattern.length > 0) {
                      if (pattern.indexOf('/') === -1) {
                          specPattern = new RegExp('(' + pattern + '[^/]*)(?!/)$', 'ig');
                      } else if (pattern.indexOf('/') === 0) {
                          specPattern = new RegExp('(' + pattern + '[^/]*)(?=/)', 'ig');
                      } else {
                          throw new Error('--filter flag seems to be in the wrong format.');
                      }
  
                      // push is usually faster than concat.
                      [].push.apply(scriptSpecs, files.filter(matchPath));
                  }
              }
              filteredArray = _.uniq(scriptSpecs);
          }
  
          return filteredArray;
      }
docs: -------------------------------- SPEC FILTERING --------------------------------