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

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

const { create } = require('./comment-tag');

const HEADER = {
  RELEASE: 'Merging this PR will publish the following release:\n\n',
  NO_RELEASE: 'Merging this PR will **not** publish a release.',
};

/**
 * Returns a function accepting a Github PR object (as returned by the Github API).
 *
 * @param commentTag
 * @param githubRepo
 * @param logger
 * @param notes
 */
const createChangelog = (
  { githubRepo, npmPackage: { name: npmPackageName } },
  {
    logger,
    envCi: { commit: gitHead },
    nextRelease: { gitTag = null, notes } = {},
  }
) => async ({ number, title }) => {
  const body =
    create(gitHead, npmPackageName, gitTag) +
    '\n' +
    (notes ? HEADER.RELEASE + notes : HEADER.NO_RELEASE);

  logger.log(`Creating changelog comment on PR "${title}"`);

  // To create a general PR comment (unassociated with a line number),
  // we must create it on the corresponding issue that GitHub creates.
  // https://stackoverflow.com/questions/16744069/create-comment-on-pull-request
  await githubRepo.createIssueComment({
    number,
    body,
  });
};

module.exports = createChangelog;