Use ESM

Author: wooorm

.gitignore

@@ -1,6 +1,5 @@
-.DS_Store
-*.log
-.nyc_output/
 coverage/
 node_modules/
+.DS_Store
+*.log
 yarn.lock

.prettierignore

@@ -1,3 +1,2 @@
 coverage/
-*.json
 *.md

index.js

@@ -1,16 +1,12 @@
-'use strict'
-
-var path = require('path')
-var gitDiffTree = require('git-diff-tree')
-var findUp = require('vfile-find-up')
-
-module.exports = diff
+import path from 'path'
+import gitDiffTree from 'git-diff-tree'
+import findUp from 'vfile-find-up'
 
 var own = {}.hasOwnProperty
 
 var previousRange
 
-function diff() {
+export default function diff() {
   var cache = {}
 
   return transform
@@ -48,19 +44,22 @@ function diff() {
       previousRange = commitRange
     }
 
+    /* c8 ignore next 3 */
     if (own.call(cache, base)) {
       tick(cache[base])
     } else {
       findUp.one('.git', file.dirname, ongit)
     }
 
     function ongit(error, git) {
-      /* istanbul ignore if - Never happens */
+      // Never happens.
+      /* c8 ignore next 3 */
       if (error) {
         return next(error)
       }
 
-      /* istanbul ignore if - Not testable in a Git repo… */
+      // Not testable in a Git repo…
+      /* c8 ignore next 3 */
       if (!git) {
         return next(new Error('Not in a git repository'))
       }
@@ -85,7 +84,8 @@ function diff() {
         if (info) {
           fp = path.resolve(root, info.path)
 
-          /* istanbul ignore else - long diffs. */
+          // Long diffs.
+          /* c8 ignore next 3 */
           if (!(fp in diffs)) {
             diffs[fp] = []
           }
@@ -133,7 +133,8 @@ function parse(data) {
   var position
   var no
 
-  /* istanbul ignore if - Should not happen, maybe if Git returns weird diffs? */
+  // Should not happen, maybe if Git returns weird diffs?
+  /* c8 ignore next 3 */
   if (!match) {
     return
   }

package.json

@@ -25,6 +25,9 @@
   "contributors": [
     "Titus Wormer <[email protected]> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
     "index.js"
   ],
@@ -33,8 +36,8 @@
     "vfile-find-up": "^5.0.0"
   },
   "devDependencies": {
+    "c8": "^7.0.0",
     "nlcst-to-string": "^2.0.0",
-    "nyc": "^15.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
@@ -43,20 +46,14 @@
     "tape": "^5.0.0",
     "to-vfile": "^6.0.0",
     "unist-util-visit": "^2.0.0",
-    "xo": "^0.38.0"
+    "xo": "^0.39.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
-    "test-api": "node test",
-    "test-coverage": "nyc --reporter lcov tape test/index.js",
+    "test-api": "node --conditions development test/index.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node --conditions development test/index.js",
     "test": "npm run format && npm run test-coverage"
   },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
-  },
   "prettier": {
     "tabWidth": 2,
     "useTabs": false,
@@ -67,8 +64,9 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
       "unicorn/prefer-number-properties": "off",
       "unicorn/no-fn-reference-in-iterator": "off",
       "unicorn/string-content": "off"

readme.md

@@ -24,6 +24,9 @@ When run outside supported CIs this plugin doesn’t do anything.
 
 ## Install
 
+This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c):
+Node 12+ is needed to use it and it must be `import`ed instead of `require`d.
+
 [npm][]:
 
 ```sh
@@ -123,7 +126,9 @@ an error, but it’s unrelated to the PR.
 
 ## API
 
-### `processor.use(diff)`
+This package exports a plugin as the default export.
+
+### `unified().use(diff)`
 
 Ignore messages emitted by plugins before `diff` for lines that did not change.
 
@@ -132,7 +137,7 @@ If there’s a `TRAVIS_COMMIT_RANGE`, `GITHUB_BASE_REF` and `GITHUB_HEAD_REF`, o
 `GITHUB_SHA` environment variable, then this plugin runs, otherwise it does
 nothing.
 
-###### TODO
+###### To do
 
 *   [ ] Add support for other CIs (ping if you want to work on this)
 *   [ ] Add non-CI support (I’m not yet sure how though)

test/index.js

@@ -1,12 +1,10 @@
-'use strict'
-
-var cp = require('child_process')
-var path = require('path')
-var promisify = require('util').promisify
-var test = require('tape')
-var rimraf = promisify(require('rimraf'))
-var vfile = require('to-vfile')
-var processor = require('./processor.js')()
+import cp from 'child_process'
+import {promises as fsPromises} from 'fs'
+import path from 'path'
+import {promisify} from 'util'
+import test from 'tape'
+import vfile from 'to-vfile'
+import {processor} from './processor.js'
 
 var exec = promisify(cp.exec)
 
@@ -45,7 +43,7 @@ test('diff() (travis)', function (t) {
     .then(() => exec('git config --global user.email').catch(setEmailAndName))
     // Add initial file.
     .then(() =>
-      processor.process(vfile({path: 'example.txt', contents: stepOne}))
+      processor().process(vfile({path: 'example.txt', contents: stepOne}))
     )
     .then((file) => {
       t.deepEqual(
@@ -70,7 +68,9 @@ test('diff() (travis)', function (t) {
     .then((result) => {
       final = result.stdout.trim()
       process.env.TRAVIS_COMMIT_RANGE = [initial, final].join('...')
-      return processor.process(vfile({path: 'example.txt', contents: stepTwo}))
+      return processor().process(
+        vfile({path: 'example.txt', contents: stepTwo})
+      )
     })
     .then((file) => {
       t.deepEqual(
@@ -81,7 +81,7 @@ test('diff() (travis)', function (t) {
     })
     // Again!
     .then(() =>
-      processor.process(vfile({path: 'example.txt', contents: stepTwo}))
+      processor().process(vfile({path: 'example.txt', contents: stepTwo}))
     )
     .then((file) => {
       t.deepEqual(
@@ -92,7 +92,7 @@ test('diff() (travis)', function (t) {
     })
     // Unstaged files.
     .then(() =>
-      processor.process(vfile({path: 'missing.txt', contents: other}))
+      processor().process(vfile({path: 'missing.txt', contents: other}))
     )
     .then((file) => {
       t.deepEqual(
@@ -112,7 +112,7 @@ test('diff() (travis)', function (t) {
 
       process.env.TRAVIS_COMMIT_RANGE = [initial, final].join('...')
 
-      return processor.process(
+      return processor().process(
         vfile({path: 'example.txt', contents: stepThree})
       )
     })
@@ -123,7 +123,7 @@ test('diff() (travis)', function (t) {
         'should deal with multiple patches'
       )
 
-      return processor.process(vfile({path: 'new.txt', contents: other}))
+      return processor().process(vfile({path: 'new.txt', contents: other}))
     })
     .then((file) => {
       t.deepEqual(
@@ -132,7 +132,7 @@ test('diff() (travis)', function (t) {
         'should deal with new files'
       )
 
-      return processor.process(vfile({path: 'new.txt', contents: other}))
+      return processor().process(vfile({path: 'new.txt', contents: other}))
     })
     // Restore
     .then(restore, restore)
@@ -143,9 +143,10 @@ test('diff() (travis)', function (t) {
 
   function restore() {
     delete process.env.TRAVIS_COMMIT_RANGE
-    return rimraf('.git')
-      .then(() => rimraf('new.txt'))
-      .then(() => rimraf('example.txt'))
+    return fsPromises
+      .rm('.git', {recursive: true})
+      .then(() => fsPromises.rm('new.txt'))
+      .then(() => fsPromises.rm('example.txt'))
   }
 })
 
@@ -175,7 +176,9 @@ test('diff() (GitHub Actions)', function (t) {
     .then(() => exec('git rev-parse HEAD'))
     .then((result) => {
       process.env.GITHUB_SHA = result.stdout.trim()
-      return processor.process(vfile({path: 'example.txt', contents: stepTwo}))
+      return processor().process(
+        vfile({path: 'example.txt', contents: stepTwo})
+      )
     })
     .then((file) => {
       t.deepEqual(
@@ -202,7 +205,9 @@ test('diff() (GitHub Actions)', function (t) {
       process.env.GITHUB_SHA = result.stdout.trim()
       process.env.GITHUB_BASE_REF = 'refs/heads/' + main
       process.env.GITHUB_HEAD_REF = 'refs/heads/other-branch'
-      return processor.process(vfile({path: 'example.txt', contents: stepFour}))
+      return processor().process(
+        vfile({path: 'example.txt', contents: stepFour})
+      )
     })
     .then((file) => {
       t.deepEqual(
@@ -222,7 +227,9 @@ test('diff() (GitHub Actions)', function (t) {
     delete process.env.GITHUB_SHA
     delete process.env.GITHUB_BASE_REF
     delete process.env.GITHUB_HEAD_REF
-    return rimraf('.git').then(() => rimraf('example.txt'))
+    return fsPromises
+      .rm('.git', {recursive: true})
+      .then(() => fsPromises.rm('example.txt'))
   }
 })
 

test/processor.js

@@ -1,11 +1,9 @@
-'use strict'
+import retext from 'retext'
+import visit from 'unist-util-visit'
+import toString from 'nlcst-to-string'
+import unifiedDiff from '../index.js'
 
-var retext = require('retext')
-var visit = require('unist-util-visit')
-var toString = require('nlcst-to-string')
-var diff = require('..')
-
-module.exports = retext().use(lorem).use(diff).freeze()
+export const processor = retext().use(lorem).use(unifiedDiff).freeze()
 
 function lorem() {
   return transformer