feat: usage of ESM imports instead of CommonJS (#271)

.github/workflows/old-test.yml

@@ -0,0 +1,43 @@
+# Special test for the oldest version of Node.js that we "support"
+# even though the linter won't actually run. Test that the command
+# line program exits cleanly.
+
+name: Old test
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [0.10.48]
+
+    steps:
+      - name: Checkout project
+        uses: actions/checkout@v2.3.4
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v2.4.0
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Cache Node dependencies
+        uses: actions/cache@v2.1.6
+        with:
+          path: ~/.npm
+          key: ${{ runner.os }}-node-${{ hashFiles('**/package.json') }}
+          restore-keys: |
+            ${{ runner.os }}-node-
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Test that the command line program exits cleanly.
+        run: ./bin/cmd.js
+        shell: bash

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [10.x, 12.x, 14.x, 16.x]
+        node-version: [12.20.0, 14.13.1, 16.0.0]
       fail-fast: false
 
     steps:

bin/cmd.js

@@ -1,4 +1,16 @@
 #!/usr/bin/env node
+/* eslint-disable no-var, no-eval */
 
-const opts = require('../options.js')
-require('standard-engine').cli(opts)
+var match = process.version.match(/v(\d+)\.(\d+)/)
+var major = parseInt(match[1], 10)
+var minor = parseInt(match[2], 10)
+
+if (major >= 12 || (major === 12 && minor >= 20)) {
+  eval('import("standard-engine")').then(function (standardEngine) {
+    eval('import("../options.js")').then(function (options) {
+      standardEngine.cli(options.default)
+    })
+  })
+} else {
+  console.error('semistandard: Node 12.20.0 or greater is required. `semistandard` did not run.')
+}

index.js

@@ -1,7 +1,8 @@
 /*! semistandard. MIT License. Feross Aboukhadijeh <https://feross.org/opensource> */
 // programmatic usage
-const Linter = require('standard-engine').linter
+import engine from 'standard-engine'
+import opts from './options.js'
 
-const opts = require('./options.js')
+const Linter = engine.linter
 
-module.exports = new Linter(opts)
+export default new Linter(opts)

options.js

@@ -1,15 +1,19 @@
-const path = require('path')
-const pkg = require('./package.json')
+import { fileURLToPath } from 'node:url'
+import { readFileSync } from 'node:fs'
+import eslint from 'eslint'
 
-module.exports = {
+const pkgUrl = new URL('./package.json', import.meta.url)
+const pkg = JSON.parse(readFileSync(pkgUrl, 'utf-8'))
+
+export default {
   // cmd, homepage, bugs all pulled from package.json
   cmd: 'semistandard',
   version: pkg.version,
   homepage: pkg.homepage,
   bugs: pkg.bugs.url,
   tagline: 'Semicolons For All!',
-  eslint: require('eslint'),
+  eslint,
   eslintConfig: {
-    configFile: path.join(__dirname, 'eslintrc.json')
+    configFile: fileURLToPath(new URL('eslintrc.json', import.meta.url))
   }
 }

package.json

@@ -14,27 +14,26 @@
     "url": "https://github.com/standard/semistandard/issues"
   },
   "dependencies": {
-    "eslint": "^7.27.0",
+    "eslint": "^7.32.0",
     "eslint-config-semistandard": "16.0.0",
     "eslint-config-standard": "16.0.3",
     "eslint-config-standard-jsx": "10.0.0",
-    "eslint-plugin-import": "^2.22.1",
+    "eslint-plugin-import": "^2.24.2",
     "eslint-plugin-node": "^11.1.0",
     "eslint-plugin-promise": "^5.1.0",
-    "eslint-plugin-react": "~7.21.5",
-    "standard-engine": "^14.0.0"
+    "eslint-plugin-react": "~7.25.1",
+    "standard-engine": "^14.0.1"
   },
   "devDependencies": {
-    "merge": "^1.2.1",
+    "merge": "^2.1.1",
     "mkdirp": "^1.0.4",
     "rimraf": "^3.0.2",
     "run-series": "^1.1.9",
     "standard": "*",
-    "tape": "^5.0.1",
-    "xtend": "^4.0.2"
+    "tape": "^5.3.1"
   },
   "engines": {
-    "node": ">=10.12.0"
+    "node": "^12.20.0 || ^14.13.1 || >=16.0.0"
   },
   "homepage": "https://github.com/standard/semistandard",
   "keywords": [
@@ -66,6 +65,7 @@
   ],
   "license": "MIT",
   "main": "index.js",
+  "type": "module",
   "repository": {
     "type": "git",
     "url": "https://github.com/standard/semistandard.git"

test/api.js

@@ -1,17 +1,18 @@
-const path = require('path')
-const semistandard = require('../')
-const test = require('tape')
-const filePath = path.resolve('./bin/cmd.js')
+import { resolve } from 'node:path'
+import test from 'tape'
+import semistandard from '../index.js'
+
+const filePath = resolve('./bin/cmd.js')
 
 test('api usage', function (t) {
   t.plan(6)
   semistandard.lintFiles(['bin/cmd.js'], {}, function (err, result) {
     t.error(err, 'no error while linting')
     t.equal(typeof result, 'object', 'result is an object')
-    t.equal(result.errorCount, 2, 'error count 2')
+    t.equal(result.errorCount, 7, 'error count 7')
 
-    t.equal(path.resolve(result.results[0].filePath), filePath, 'error filepath correct')
-    t.equal(result.results[0].messages[0].message, 'Missing semicolon.', 'first mising semicolon message')
-    t.equal(result.results[0].messages[0].message, 'Missing semicolon.', 'second mising semicolon message')
+    t.equal(resolve(result.results[0].filePath), filePath, 'error filepath correct')
+    t.equal(result.results[0].messages[0].message, 'Missing semicolon.', 'first missing semicolon message')
+    t.equal(result.results[0].messages[0].message, 'Missing semicolon.', 'second missing semicolon message')
   })
 })

test/clone.js

@@ -8,16 +8,16 @@
  * VERSION BUMP.)
  */
 
-const cp = require('child_process')
-const extend = require('xtend')
-const mkdirp = require('mkdirp')
-const path = require('path')
-const rimraf = require('rimraf')
-const series = require('run-series')
-const test = require('tape')
+import cp from 'node:child_process'
+import path from 'node:path'
+import { fileURLToPath } from 'node:url'
+import mkdirp from 'mkdirp'
+import rimraf from 'rimraf'
+import series from 'run-series'
+import test from 'tape'
 
-const TMP = path.join(__dirname, '..', 'tmp')
-const SEMISTANDARD = path.join(__dirname, '..', 'bin', 'cmd.js')
+const TMP = fileURLToPath(new URL('../tmp', import.meta.url))
+const SEMISTANDARD = fileURLToPath(new URL('../bin/cmd.js', import.meta.url))
 
 // const URLS = require('./semistandard-repos.json')
 const URLS = [
@@ -65,7 +65,7 @@ test('lint repos', function (t) {
 })
 
 function spawn (command, args, opts, cb) {
-  const child = cp.spawn(command, args, extend({ stdio: 'inherit' }, opts))
+  const child = cp.spawn(command, args, { stdio: 'inherit', ...opts })
   child.on('error', cb)
   child.on('close', function (code) {
     if (code !== 0) cb(new Error('non-zero exit code: ' + code))