Function checkLinksInFile

build-system/tasks/check-links.js:97–181

* Checks a given markdown file for dead links. * * @param {string} file * @return {!Promise<{file: string, containsDeadLinks: boolean}>}

(file)

 * @return {!Promise<{file: string, containsDeadLinks: boolean}>}
 */
function checkLinksInFile(file) {
  let markdown = fs.readFileSync(file).toString();

  // Links inside <code> blocks are illustrative and not always valid. Must be
  // removed because markdownLinkCheck() does not ignore them like <pre> blocks.
  markdown = markdown.replace(/<code>([^]*?)<\/code>/g, '');

  const opts = {
    // Relative links start at the markdown file's path.
    baseUrl: 'file://' + path.dirname(path.resolve(file)),
    ignorePatterns: [
      // Please note: This list is for links that are present many times in the repository.
      // If a single link is failing, you can remove it directly using a surrounding
      // comment directive markdown-link-check-disable / markdown-link-check-enable.

      // Localhost links don't work unless a `amp` server is running.
      {pattern: /localhost/},
      // codepen returns a 503 for these link checks
      {pattern: /https:\/\/codepen.*/},
      // developers.google.com links are assumed to exist
      {pattern: /https:\/\/developers.google.com\/.*/},
      // anchor links should be ignored
      {pattern: /^#/},
      // GitHub PRs and Issues can be assumed to exist
      {pattern: /https:\/\/github.com\/ampproject\/amphtml\/(pull|issue)\/.*/},
      // Templated links are merely used to generate other markdown files.
      {pattern: /\$\{[a-z]*\}/},
      {pattern: /https:.*?__component_name\w*__/},
    ],
    httpHeaders: [
      {
        urls: ['https://'],
        headers: {
          'User-Agent': USER_AGENT,
        },
      },
    ],
    // Ignore:
    // - 403 [Forbidden], some sites block automated requests.
    // - 429 [Too Many Requests], some sites rate-limit requests.
    aliveStatusCodes: [200, 403, 429],
  };

  return new Promise((resolve, reject) => {
    markdownLinkCheck(markdown, opts, (err, results) => {
      if (err) {
        reject(err);
        return;
      }
      let containsDeadLinks = false;
      for (const result of results) {
        const {link, statusCode} = result;
        let {status} = result;
        // Skip links to files that were introduced by the PR.
        if (isLinkToFileIntroducedByPR(link) && status == 'dead') {
          // Log links with the correct github base as alive, otherwise flag deadlinks.
          const isValid = filesIntroducedByPr.some((file) => {
            return link === GITHUB_BASE_PATH + file;