code: protected function onAddFailure($e)
      {
          $this->writeProgressWithColor('fg-red,bold', 'F');
  
          $this->failure = $e;
          $this->lastTestFailed = true;
          $this->flawless = false;
      }
docs: Invoked when an assertion fails in the test runner.
  
  @param AssertionFailedError $e