index.js

const { getInput, setFailed, debug, error } = require('@actions/core');
const { getOctokit, context } = require('@actions/github');

const { BAD_KEYWORDS } = require('./constants');

function filterCommit(commit) {
  commit = commit.toLowerCase();
  const result = [];

  for (const keyword of BAD_KEYWORDS) {
    if (commit.indexOf(keyword) != -1) {
      result.push(keyword);
    }
  }

  return result;
}

async function verifyCommits(repoToken) {
  const client = getOctokit(repoToken);
  const { data: commits } = await client.rest.pulls.listCommits({
    owner: context.repo.owner,
    repo: context.repo.repo,
    pull_number: context.issue.number
  });

  debug(`There are ${commits.length} commits in this pull request`);

  let badCommits = 0;

  for (const commit of commits) {
    const { message } = commit.commit;
    const badKeywords = filterCommit(message);

    if (badKeywords.length) {
      error(`commit message "${message}" contains ${badKeywords.join()}`);
      badCommits++;
    }
  }

  if (badCommits) {
    throw new Error(`${badCommits} bad commit(s) encountered. Please fix the above errors`);
  }
}

async function main() {
  try {
    const repoToken = getInput('repo-token', { required: true });

    debug('Received repo token');

    await verifyCommits(repoToken);
  } catch (e) {
    setFailed(`Action failed with error: ${e.message}`);
  }
}

main();