dangerfile.js

const PR_LINK = `([#${danger.github.pr.number}](${danger.github.pr.html_url}))`;

const CHANGELOG_SUMMARY_TITLE = `Instructions and example for changelog`;
const CHANGELOG_BODY = `Please add an entry to \`CHANGELOG.md\` to the "Unreleased" section. Make sure the entry includes this PR's number.

Example:`;

const CHANGELOG_END_BODY = `If none of the above apply, you can opt out of this check by adding \`#skip-changelog\` to the PR description.`;

function getCleanTitleWithPrLink() {
  const title = danger.github.pr.title;
  return title.split(": ").slice(-1)[0].trim().replace(/\.+$/, "") + ` ` + PR_LINK;
}

function getChangelogDetailsHtml() {
  return `
### ${CHANGELOG_SUMMARY_TITLE}

${CHANGELOG_BODY}

\`\`\`markdown
- ${getCleanTitleWithPrLink()}
\`\`\`

${CHANGELOG_END_BODY}
`;
}

function getChangelogDetailsTxt() {
  return (
    CHANGELOG_SUMMARY_TITLE +
    "\n" +
    CHANGELOG_BODY +
    "\n" +
    getCleanTitleWithPrLink() +
    "\n" +
    CHANGELOG_END_BODY
  );
}

function HasPermissionToComment() {
  return (
    danger.github.pr.head.repo.git_url == danger.github.pr.base.repo.git_url
  );
}

async function containsChangelog(path) {
  const contents = await danger.github.utils.fileContents(path);
  return contents.includes(PR_LINK);
}

async function checkChangelog() {
  const skipChangelog =
    danger.github && (danger.github.pr.body + "").toLowerCase().includes("#skip-changelog");
  if (skipChangelog) {
    return;
  }

  const hasChangelog = await containsChangelog("CHANGELOG.md");

  if (!hasChangelog) {
    if (HasPermissionToComment()) {
      fail("Please consider adding a changelog entry for the next release.");
      markdown(getChangelogDetailsHtml());
    } else {
      //Fallback
      console.log(
        "Please consider adding a changelog entry for the next release."
      );
      console.log(getChangelogDetailsTxt());
      process.exitCode = 1;
    }
  }
}

async function checkIfFeature() {
  const title = danger.github.pr.title;
  if (title.startsWith("feat:") && HasPermissionToComment()) {
    message(
      'Do not forget to update <a href="https://github.com/getsentry/sentry-docs">Sentry-docs</a> with your feature once the pull request gets approved.'
    );
  }
}

async function checkAll() {
  // See: https://spectrum.chat/danger/javascript/support-for-github-draft-prs~82948576-ce84-40e7-a043-7675e5bf5690
  const isDraft = danger.github.pr.mergeable_state === "draft";

  if (isDraft) {
    return;
  }

  await checkIfFeature();
  await checkChangelog();
}

schedule(checkAll);