code: function selectorTagNameSpyBefore(tagName) {
                      /*jshint validthis: true */
  
                      var context = phantomas.getDOMPath(this);
  
                      phantomas.incrMetric('DOMqueriesByTagName');
                      phantomas.addOffender('DOMqueriesByTagName', '%s (in %s)', tagName, context);
  
                      phantomas.enterContext({
                          type: 'getElementsByTagName',
                          callDetails: {
                              context: {
                                  length: 1,
                                  elements: [context]
                              },
                              arguments: [tagName]
                          },
                          backtrace: phantomas.getBacktrace()
                      });
                  }
docs: selectors by tag name