Convert package to ESM (#113)

Converts this package to an ESM module. Kudos to [this guide](https://tsmx.net/convert-existing-nodejs-project-from-commonjs-to-esm/) and this issue: TypeStrong/ts-node#1997

In our organization, this is only possible for this package because it is not used anywhere else, and we rely on CommonJS extensively.

Changes in detail:
- Update `package.json` for ESM compatibility
- Replace all `require()` with `import` statements
- Add `.js` file extension to all file imports in TypeScript source files
- Update TypeScript, ESLint, and Jest configs for ESM compatibility and recommended best practices
  - TypeScript (`tsconfig.json`)
    - Update the `module`/`moduleResolution` fields to `Node16`.
    - I chose `Node16` over `NodeNext`, as the behavior of `NodeNext` may change in the future. See [here](https://www.typescriptlang.org/docs/handbook/modules/reference.html#node16-nodenext) for details.
  - ESLint (`.eslintrc.cjs`)
    - `parseOptions.sourceType = 'module'`
  - Jest (`jest.config.cjs`)
    - Update the `moduleNameMapper` to strip the `.js` from local file imports. See [here](https://kulshekhar.github.io/ts-jest/docs/guides/esm-support/) for details.
- Replace `ts-node` with `tsx`, which has better ESM compatibility.
  - Specifically, the former does not work with Node v20 at the moment: TypeStrong/ts-node#1997
- Update `jest-it-up`
  - This is so that we can use its `--config` option (thank you @PeterYinusa! rbardini/jest-it-up#12)  to target our new `.cjs` config file.

Author: rekmarks

.eslintrc.js renamed to .eslintrc.cjs

@@ -3,6 +3,10 @@ module.exports = {
 
   extends: ['@metamask/eslint-config', '@metamask/eslint-config-nodejs'],
 
+  parserOptions: {
+    sourceType: 'module',
+  },
+
   rules: {
     // This makes integration tests easier to read by allowing setup code and
     // assertions to be grouped together better

.prettierrc.js renamed to .prettierrc.cjs

@@ -1,4 +1,4 @@
 #!/usr/bin/env node
 
-/* eslint-disable-next-line import/no-unassigned-import,import/no-unresolved */
-require('../dist/cli');
+// eslint-disable-next-line import/no-unassigned-import,import/no-unresolved
+import '../dist/cli';

bin/create-release-branch.js

@@ -3,6 +3,7 @@
  * https://jestjs.io/docs/configuration
  */
 
+// This file needs to be .cjs for compatibility with jest-it-up.
 module.exports = {
   // All imported modules in your tests should be mocked automatically
   // automock: false,
@@ -87,7 +88,11 @@ module.exports = {
   // ],
 
   // A map from regular expressions to module names or to arrays of module names that allow to stub out resources with a single module
-  // moduleNameMapper: {},
+  moduleNameMapper: {
+    // Strip the file extension from imports, so that e.g. `import { foo } from './foo.js'`
+    // becomes `import { foo } from './foo'`. This is for compatibility with ESM.
+    '^(\\.\\.?\\/.+)\\.js$': '$1',
+  },
 
   // An array of regexp pattern strings, matched against all module paths before considered 'visible' to the module loader
   // modulePathIgnorePatterns: [],

jest.config.js renamed to jest.config.cjs

@@ -6,6 +6,8 @@
     "type": "git",
     "url": "https://github.com/MetaMask/create-release-branch.git"
   },
+  "type": "module",
+  "exports": null,
   "bin": "bin/create-release-branch.js",
   "files": [
     "bin/",
@@ -19,12 +21,12 @@
     "lint:fix": "yarn lint:eslint --fix && yarn lint:misc --write",
     "lint:misc": "prettier '**/*.json' '**/*.md' '!CHANGELOG.md' '**/*.yml' '!.yarnrc.yml' --ignore-path .gitignore --no-error-on-unmatched-pattern",
     "prepack": "./scripts/prepack.sh",
-    "test": "jest && jest-it-up",
+    "test": "jest && jest-it-up --config jest.config.cjs",
     "test:watch": "jest --watch"
   },
   "dependencies": {
     "@metamask/action-utils": "^1.0.0",
-    "@metamask/utils": "^8.1.0",
+    "@metamask/utils": "^8.2.1",
     "debug": "^4.3.4",
     "execa": "^5.1.1",
     "pony-cause": "^2.1.9",
@@ -58,15 +60,15 @@
     "eslint-plugin-node": "^11.1.0",
     "eslint-plugin-prettier": "^4.2.1",
     "jest": "^29.5.0",
-    "jest-it-up": "^2.0.2",
+    "jest-it-up": "^3.0.0",
     "jest-when": "^3.5.2",
     "nanoid": "^3.3.4",
     "prettier": "^2.2.1",
     "prettier-plugin-packagejson": "^2.3.0",
     "rimraf": "^4.0.5",
     "stdio-mock": "^1.2.0",
     "ts-jest": "^29.1.0",
-    "ts-node": "^10.7.0",
+    "tsx": "^4.6.1",
     "typescript": "~5.1.6"
   },
   "packageManager": "[email protected]",
@@ -79,7 +81,8 @@
   },
   "lavamoat": {
     "allowScripts": {
-      "@lavamoat/preinstall-always-fail": false
+      "@lavamoat/preinstall-always-fail": false,
+      "tsx>esbuild": false
     }
   }
 }

package.json

@@ -1,4 +1,4 @@
-import { main } from './main';
+import { main } from './main.js';
 
 /**
  * The entrypoint to this tool.

src/cli.ts

@@ -1,7 +1,7 @@
 import { when } from 'jest-when';
-import { determineEditor } from './editor';
-import * as envModule from './env';
-import * as miscUtils from './misc-utils';
+import { determineEditor } from './editor.js';
+import * as envModule from './env.js';
+import * as miscUtils from './misc-utils.js';
 
 jest.mock('./env');
 jest.mock('./misc-utils');

src/editor.test.ts

@@ -1,5 +1,5 @@
-import { getEnvironmentVariables } from './env';
-import { debug, resolveExecutable } from './misc-utils';
+import { getEnvironmentVariables } from './env.js';
+import { debug, resolveExecutable } from './misc-utils.js';
 
 /**
  * Information about the editor present on the user's computer.

src/editor.ts

@@ -1,4 +1,4 @@
-import { getEnvironmentVariables } from './env';
+import { getEnvironmentVariables } from './env.js';
 
 describe('env', () => {
   describe('getEnvironmentVariables', () => {

src/env.test.ts

@@ -3,7 +3,7 @@ import path from 'path';
 import { rimraf } from 'rimraf';
 import { when } from 'jest-when';
 import * as actionUtils from '@metamask/action-utils';
-import { withSandbox } from '../tests/helpers';
+import { withSandbox } from '../tests/helpers.js';
 import {
   readFile,
   writeFile,
@@ -12,7 +12,7 @@ import {
   fileExists,
   ensureDirectoryPathExists,
   removeFile,
-} from './fs';
+} from './fs.js';
 
 jest.mock('@metamask/action-utils');