lintcommit.js

// Checks that a PR title conforms to conventional commits
// (https://www.conventionalcommits.org/).
//
// To run self-tests, run this script:
//
//     node lintcommit.js test

import { readFileSync, appendFileSync } from "fs";

const types = new Set([
  "build",
  "chore",
  "ci",
  "config",
  "deps",
  "docs",
  "feat",
  "fix",
  "perf",
  "refactor",
  "revert",
  "style",
  "test",
  "types",
]);

const scopes = new Set(["sdk", "examples"]);

/**
 * Checks that a pull request title, or commit message subject, follows the expected format:
 *
 *      type(scope): message
 *
 * Returns undefined if `title` is valid, else an error message.
 */
function validateTitle(title) {
  const parts = title.split(":");
  const subject = parts.slice(1).join(":").trim();

  if (title.startsWith("Merge")) {
    return undefined;
  }

  if (parts.length < 2) {
    return "missing colon (:) char";
  }

  const typeScope = parts[0];

  const [type, scope] = typeScope.split(/\(([^)]+)\)$/);

  if (/\s+/.test(type)) {
    return `type contains whitespace: "${type}"`;
  } else if (!types.has(type)) {
    return `invalid type "${type}"`;
  } else if (!scope && typeScope.includes("(")) {
    return `must be formatted like type(scope):`;
  } else if (scope && scope.length > 30) {
    return "invalid scope (must be <=30 chars)";
  } else if (scope && /[^- a-z0-9]+/.test(scope)) {
    return `invalid scope (must be lowercase, ascii only): "${scope}"`;
  } else if (scope && !scopes.has(scope)) {
    return `invalid scope "${scope}" (valid scopes are ${Array.from(scopes).join(", ")})`;
  } else if (subject.length === 0) {
    return "empty subject";
  } else if (subject.length > 50) {
    return "invalid subject (must be <=50 chars)";
  }

  return undefined;
}

function run() {
  const eventData = JSON.parse(
    readFileSync(process.env.GITHUB_EVENT_PATH, "utf8"),
  );
  const pullRequest = eventData.pull_request;

  // console.log(eventData)

  if (!pullRequest) {
    console.info("No pull request found in the context");
    return;
  }

  const title = pullRequest.title;

  const failReason = validateTitle(title);
  const msg = failReason
    ? `
Invalid pull request title: \`${title}\`

* Problem: ${failReason}
* Expected format: \`type(scope): subject...\`
    * type: one of (${Array.from(types).join(", ")})
    * scope: optional, lowercase, <30 chars
    * subject: must be <50 chars
* Hint: *close and re-open the PR* to re-trigger CI (after fixing the PR title).
`
    : `Pull request title matches the expected format`;

  if (process.env.GITHUB_STEP_SUMMARY) {
    appendFileSync(process.env.GITHUB_STEP_SUMMARY, msg);
  }

  if (failReason) {
    console.error(msg);
    process.exit(1);
  } else {
    console.info(msg);
  }
}

function _test() {
  const tests = {
    " foo(scope): bar": 'type contains whitespace: " foo"',
    "build: update build process": undefined,
    "chore: update dependencies": undefined,
    "ci: configure CI/CD": undefined,
    "config: update configuration files": undefined,
    "deps: bump aws-sdk group with 5 updates": undefined,
    "docs: update documentation": undefined,
    "feat(sdk): add new feature": undefined,
    "feat(sdk):": "empty subject",
    "feat foo):": 'type contains whitespace: "feat foo)"',
    "feat(foo)): sujet": 'invalid type "feat(foo))"',
    "feat(foo: sujet": 'invalid type "feat(foo"',
    "feat(Q Foo Bar): bar":
      'invalid scope (must be lowercase, ascii only): "Q Foo Bar"',
    "feat(sdk): bar": undefined,
    "feat(sdk): x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x ":
      "invalid subject (must be <=50 chars)",
    "feat: foo": undefined,
    "fix: foo": undefined,
    "fix(sdk): resolve issue": undefined,
    "foo (scope): bar": 'type contains whitespace: "foo "',
    "invalid title": "missing colon (:) char",
    "perf: optimize performance": undefined,
    "refactor: improve code structure": undefined,
    "revert: feat: add new feature": undefined,
    "style: format code": undefined,
    "test: add new tests": undefined,
    "types: add type definitions": undefined,
    "Merge staging into feature/lambda-get-started": undefined,
    "feat(foo): fix the types":
      'invalid scope "foo" (valid scopes are sdk, examples)',
  };

  let passed = 0;
  let failed = 0;

  for (const [title, expected] of Object.entries(tests)) {
    const result = validateTitle(title);
    if (result === expected) {
      console.log(`✅ Test passed for "${title}"`);
      passed++;
    } else {
      console.log(
        `❌ Test failed for "${title}" (expected "${expected}", got "${result}")`,
      );
      failed++;
    }
  }

  console.log(`\n${passed} tests passed, ${failed} tests failed`);
}

function main() {
  const mode = process.argv[2];

  if (mode === "test") {
    _test();
  } else {
    run();
  }
}

main();