semantic-release-github-pr/src/delete-changelog.js

A `semantic-release` plugin that creates a changelog comment on Github PRs.

const debug = require('debug')('semantic-release:github-pr');
const { parse } = require('./comment-tag');

/**
 * We could just consider all previous comments stale, but to be compatible
 * with `semantic-release-monorepo`, we take care not to remove comments
 * made with the same `gitHead` but a different `npmPackageName`. Comments
 * fitting that criteria would only exist in a monorepo scenario.
 *
 * Lastly, the "no release" comment, as identified by a `null` git tag, should
 * always be wiped because we'd only want a single one in any scenario.
 * @param {String} gitHead
 * @param {String} npmPackageName
 * @param {Boolean} skipNoRelease Whether to delete "no release" comments.
 * @returns {Function} Returns a predicate function accepting a string to match
 * for a stale comment.
 */
const matchStaleComment = (
  gitHead,
  npmPackageName,
  skipNoRelease
) => comment => {
  const result = parse(comment);

  debug(`Comment is a PR changelog: %o`, !!result);
  if (!result) {
    return false;
  }

  const matchesGitHead = result.matchesGitHead(gitHead);
  const matchesPackageName = result.matchesPackageName(npmPackageName);
  const isNoRelease = result.matchesGitTag('null');

  debug(`Comment matches git head: %o`, matchesGitHead);
  debug(`Comment matches npm package name: %o`, matchesPackageName);
  debug(`Comment is "no release" comment: %o`, isNoRelease);

  return (
    (!matchesGitHead && matchesPackageName) || (!skipNoRelease && isNoRelease)
  );
};

/**
 * To keep from spamming each PR with comments, we identify any previous
 * comments posted by this plugin (using `commentTag`) and delete them.
 *
 * Returns a function accepting a Github PR object (as returned by the Github API).
 */
const deleteStaleChangelogs = skipNoRelease => (
  { githubRepo, npmPackage: { name: npmPackageName } },
  { logger, envCi: { commit: gitHead } }
) => async ({ number, title }) => {
  const { data: comments } = await githubRepo.getIssueComments({ number });
  const isStaleComment = matchStaleComment(
    gitHead,
    npmPackageName,
    skipNoRelease
  );

  comments.forEach(async ({ id, body }) => {
    debug(`Checking PR comment %o for stale changelog message...`, id);
    if (isStaleComment(body)) {
      logger.log(`Deleting stale changelog comment on PR "${title}"`);
      await githubRepo.deleteIssueComment({ id });
    }
  });
};

module.exports = deleteStaleChangelogs;