Previously, the `URLS_TO_REDIRECT.txt` file was expected to not contain any empty lines. This could easily result in test errors when updating the file, since it is common for IDEs/editors to automatically ensure there is an empty line at the end of a saved file ([example failure][1]). This commit updates the test helpers to be able to cope with empty or whitespace-only lines in `URLS_TO_REDIRECT.txt` by ignoring such lines. [1]: https://circleci.com/gh/angular/angular/965534 PR Close #41680