function wfLineBreakInLink(ast, file, setting) {
  const msg = 'Link contains unescaped whitespace or accidental line break.';
  const RE_WHITESPACE = /\s/;
  visit(ast, 'html', function(node) {
    const anchorTag = node.value.match(/<a((.|\n)*?)>/i);
    if (anchorTag && anchorTag[1]) {
      const href = anchorTag[1].match(/href=["|']((.|\n)*?)["|']/i);
      if (href && href[1] && RE_WHITESPACE.test(href[1])) {
        file.message(msg, node);
      }
    }
  });
}
Remark Lint Test - check if links have whitespace or line breaks.

@param {Object} ast
@param {Object} file
@param {Object} setting