Convert this library to ES Modules

Author: willdurand

.eslintrc

@@ -16,9 +16,8 @@
         ]
       }
     ],
-    "import/extensions": ["error", "never", {
-      "json": "always",
-    }],
+    // Disabled due to https://github.com/import-js/eslint-plugin-import/issues/2104
+    "import/extensions": [0, "never"],
     // This rule conflicts with our convention.
     "jest/valid-describe": "off",
     // This is not needed for this project.
@@ -32,20 +31,13 @@
     "@typescript-eslint/explicit-function-return-type": "off",
     "@typescript-eslint/no-explicit-any": "error",
     "@typescript-eslint/explicit-member-accessibility": "off",
-    "import/no-unresolved": ["error", {
-      ignore: ['estree'],
-    }],
+    // This is sad but we have to disable this rule to allow TS to generate
+    // correct a ESM package.
+    "import/no-unresolved": "off",
     // This rule is annoying and does not add any value.
     "@typescript-eslint/camelcase": "off",
     "@typescript-eslint/ban-ts-comment": ["error", {
       "ts-expect-error": "allow-with-description",
-    }],
-  },
-  "settings": {
-    "import/resolver": {
-      "node": {
-        "extensions": [".js", ".ts"]
-      }
-    }
+    }]
   }
 }

jest.config.js

@@ -1,5 +1,9 @@
-module.exports = {
+export default {
   preset: 'ts-jest',
+  moduleNameMapper: {
+    // Replace imports ending with `.js` with imports without extensions.
+    '^(\\.{1,2}/.*)\\.js$': '$1',
+  },
   testEnvironment: 'node',
   testPathIgnorePatterns: ['<rootDir>/dist/', '<rootDir>/node_modules/'],
 };

package.json

@@ -2,10 +2,16 @@
   "name": "addons-scanner-utils",
   "version": "7.0.0",
   "description": "Various addons related helpers to build CLIs.",
-  "main": "dist/index.js",
-  "types": "dist/index.d.ts",
+  "type": "module",
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "exports": {
+    ".": "./dist/index.js",
+    "./io": "./dist/io/index.js",
+    "./test-helpers": "./dist/test-helpers.js"
+  },
   "files": [
-    "dist/**/*"
+    "dist/**"
   ],
   "author": "Mozilla Add-ons Team",
   "license": "MPL-2.0",
@@ -30,7 +36,6 @@
     "@types/express": "4.17.13",
     "@types/jest": "^27.0.0",
     "@types/node": "^14.0.0",
-    "@types/safe-compare": "^1.1.0",
     "@types/sinon": "^10.0.0",
     "@types/supertest": "^2.0.8",
     "@typescript-eslint/eslint-plugin": "^5.0.0",
@@ -50,12 +55,12 @@
     "supertest": "^6.0.0",
     "ts-jest": "^28.0.0",
     "type-coverage": "^2.3.0",
-    "typescript": "^4.0.0"
+    "typescript": "^4.7.2"
   },
   "scripts": {
     "eslint": "eslint --ext ts --ext js src/",
     "lint": "yarn eslint",
-    "prepack": "rimraf dist/ && tsc --outDir dist/ && rimraf dist/**/*.spec.* dist/*.spec.*",
+    "prepack": "rimraf dist/ && tsc && rimraf dist/**/*.spec.* dist/*.spec.*",
     "prettier": "prettier --write '**'",
     "prettier-ci": "prettier --list-different '**' || (echo '\n\nThis failure means you did not run `yarn prettier-dev` before committing\n\n' && exit 1)",
     "prettier-dev": "pretty-quick --branch master",

src/@types/safe-compare/index.d.ts

@@ -0,0 +1,7 @@
+// The `@types/safe-compare` package does not declare a module and that breaks
+// the type checker...
+declare module 'safe-compare' {
+  function safeCompare(a: string, b: string): boolean;
+
+  export = safeCompare;
+}

src/const.spec.ts renamed to src/constants.spec.ts

@@ -1,6 +1,6 @@
-import { ECMA_VERSION } from './const';
+import { ECMA_VERSION } from './constants.js';
 
-describe(__filename, () => {
+describe('constants', () => {
   it('exports an ECMA_VERSION constant', () => {
     expect(ECMA_VERSION).toEqual(13);
   });

src/const.ts renamed to src/constants.ts

@@ -8,9 +8,9 @@ import {
   RequestWithFiles,
   createApiError,
   createExpressApp,
-} from './functions';
+} from './functions.js';
 
-describe(__filename, () => {
+describe('functions', () => {
   describe('createApiError', () => {
     it('returns an API error with a message', () => {
       const message = 'oops, error';

src/functions.spec.ts

@@ -1,5 +1,5 @@
-export * from './const';
-export * from './functions';
-export * from './io';
-export * from './stdio';
-export * from './errors';
+export * from './constants.js';
+export * from './functions.js';
+export * from './io/index.js';
+export * from './stdio.js';
+export * from './errors.js';

src/index.ts

@@ -1,8 +1,8 @@
-import { IOBase } from './base';
-import { FLAGGED_FILE_MAGIC_NUMBERS_LENGTH } from './const';
-import { createFakeStderr } from '../test-helpers';
+import { IOBase } from './base.js';
+import { FLAGGED_FILE_MAGIC_NUMBERS_LENGTH } from './constants.js';
+import { createFakeStderr } from '../test-helpers.js';
 
-describe(__filename, () => {
+describe('io/base', () => {
   const createIOBase = ({
     filePath = 'foo/bar/',
     stderr = createFakeStderr(),

src/io/base.spec.ts

@@ -2,8 +2,11 @@ import { Readable } from 'stream';
 
 import { oneLine } from 'common-tags';
 
-import { FLAGGED_FILE_MAGIC_NUMBERS_LENGTH, MAX_FILE_SIZE_MB } from './const';
-import { Stderr } from '../stdio';
+import {
+  FLAGGED_FILE_MAGIC_NUMBERS_LENGTH,
+  MAX_FILE_SIZE_MB,
+} from './constants.js';
+import { Stderr } from '../stdio.js';
 
 type ScanFileFunction = (_path: string, isDirectory: boolean) => boolean;