public function parse_url_component_testcases() {
    // 0: The URL, 1: The requested component, 2: The expected resulting structure.
    return array(
      array( self::FULL_TEST_URL, PHP_URL_SCHEME, 'http' ),
      array( self::FULL_TEST_URL, PHP_URL_USER, 'username' ),
      array( self::FULL_TEST_URL, PHP_URL_PASS, 'password' ),
      array( self::FULL_TEST_URL, PHP_URL_HOST, 'host.name' ),
      array( self::FULL_TEST_URL, PHP_URL_PORT, 9090 ),
      array( self::FULL_TEST_URL, PHP_URL_PATH, '/path' ),
      array( self::FULL_TEST_URL, PHP_URL_QUERY, 'arg1=value1&arg2=value2' ),
      array( self::FULL_TEST_URL, PHP_URL_FRAGMENT, 'anchor' ),

      // < PHP 5.4.7: Schemeless URL.
      array( '//example.com/path/', PHP_URL_HOST, 'example.com' ),
      array( '//example.com/path/', PHP_URL_PATH, '/path/' ),
      array( '//example.com/', PHP_URL_HOST, 'example.com' ),
      array( '//example.com/', PHP_URL_PATH, '/' ),
      array( 'http://example.com//path/', PHP_URL_HOST, 'example.com' ),
      array( 'http://example.com//path/', PHP_URL_PATH, '//path/' ),

      // < PHP 5.4.7: Scheme separator in the URL.
      array( 'http://example.com/http://example.net/', PHP_URL_HOST, 'example.com' ),
      array( 'http://example.com/http://example.net/', PHP_URL_PATH, '/http://example.net/' ),
      array( '/path/http://example.net/', PHP_URL_HOST, null ),
      array( '/path/http://example.net/', PHP_URL_PATH, '/path/http://example.net/' ),

      // < PHP 5.4.7: IPv6 literals in schemeless URLs are handled incorrectly.
      array( '//[::FFFF::127.0.0.1]/', PHP_URL_HOST, '[::FFFF::127.0.0.1]' ),
      array( '//[::FFFF::127.0.0.1]/', PHP_URL_PATH, '/' ),

      // PHP's parse_url() calls this an invalid URL, we handle it as a path.
      array( '/://example.com/', PHP_URL_PATH, '/://example.com/' ),

      // Schemeless URL containing colons cause parse errors in PHP 7+.
      array( '//fonts.googleapis.com/css?family=Open+Sans:400&subset=latin', PHP_URL_HOST, 'fonts.googleapis.com' ),
      array( '//fonts.googleapis.com/css?family=Open+Sans:400&subset=latin', PHP_URL_PORT, null ),
      array( '//fonts.googleapis.com/css?family=Open+Sans:400&subset=latin', PHP_URL_PATH, '/css' ),
      array( '//fonts.googleapis.com/css?family=Open+Sans:400&subset=latin', PHP_URL_QUERY, 'family=Open+Sans:400&subset=latin' ),
      array( '//fonts.googleapis.com/css?family=Open+Sans:400', PHP_URL_HOST, 'fonts.googleapis.com' ),  // 25
      array( '//fonts.googleapis.com/css?family=Open+Sans:400', PHP_URL_PORT, null ),
      array( '//fonts.googleapis.com/css?family=Open+Sans:400', PHP_URL_PATH, '/css' ),                  // 27
      array( '//fonts.googleapis.com/css?family=Open+Sans:400', PHP_URL_QUERY, 'family=Open+Sans:400' ), // 28

      // Empty string or non-string passed in.
      array( '', PHP_URL_PATH, '' ),
      array( '', PHP_URL_QUERY, null ),
      array( 123, PHP_URL_PORT, null ),
      array( 123, PHP_URL_PATH, '123' ),
    );
  }