Cover the rest of normalize_url() with unit tests
Cover the rest of get_url_domain() with unit tests
Cover the rest of meta_refresh_url_from_html() with unit tests
Cover the rest of link_canonical_url_from_html() with unit tests
Test if URL is defined
Cover the rest of url_and_data_after_redirects() with unit tests
Test if URL is defined
Cover all_url_variants() with unit tests