Make brotli optional

.travis.yml

@@ -1,5 +1,7 @@
 language: node_js
 node_js:
+  - 12 # Latest
+  - 10 # LTS
   - 8
 cache:
   directories:

package.json

@@ -37,7 +37,6 @@
   "license": "MIT",
   "dependencies": {
     "axios": "^0.19.0",
-    "brotli-size": "0.1.0",
     "bytes": "^3.1.0",
     "ci-env": "^1.4.0",
     "commander": "^2.20.0",
@@ -64,6 +63,7 @@
     "babel-preset-es2015": "^7.0.0-beta.3",
     "babel-preset-stage-3": "^7.0.0-beta.3",
     "babel-traverse": "^7.0.0-beta.3",
+    "bundlesize-plugin-brotli": "^1.0.0",
     "execa": "^2.0.1",
     "husky": "^0.14.3",
     "lint-staged": "^7.1.1",

packages/bundlesize-plugin-brotli/index.js

@@ -0,0 +1,3 @@
+const brotliSize = require('brotli-size')
+
+module.exports = { sync: brotliSize.sync }

packages/bundlesize-plugin-brotli/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "bundlesize-plugin-brotli",
+  "version": "1.0.0",
+  "description": "Plugin to use brotli compression with bundlesize",
+  "main": "index.js",
+  "keywords": [],
+  "author": "",
+  "license": "MIT",
+  "dependencies": {
+    "brotli-size": "0.1.0"
+  }
+}

packages/bundlesize-plugin-brotli/readme.md

@@ -0,0 +1,56 @@
+<p align="center">
+  <img src="https://cdn.rawgit.com/siddharthkp/bundlesize/master/art/logo.png" height="200px">
+  <br><br>
+  <b>Plugin to use brotli compression with bundlesize on Node < 10.6.0</b>
+  <br>
+</p>
+
+&nbsp;
+
+#### Note:
+
+If you are using Node version >= 10.16.0, you do not need this plugin.
+
+&nbsp;
+
+#### Install
+
+```sh
+npm install bundlesize-plugin-brotli --save-dev
+
+# or
+
+yarn add bundlesize-plugin-brotli --dev
+```
+
+&nbsp;
+
+#### Setting up bundlesize
+
+&nbsp;
+
+See bundlesize usage here: https://github.com/siddharthkp/bundlesize
+
+&nbsp;
+
+#### Using brotli compression
+
+&nbsp;
+
+By default, bundlesize `gzips` your build files before comparing.
+
+If you are using `brotli` instead of gzip, you can specify that with each file:
+
+```json
+{
+  "files": [
+    {
+      "path": "./build/vendor.js",
+      "maxSize": "5 kB",
+      "compression": "brotli"
+    }
+  ]
+}
+```
+
+&nbsp;

src/brotli.js

@@ -0,0 +1,48 @@
+const { error } = require('prettycli')
+const zlib = require('zlib')
+
+const config = require('./config')
+
+function getBrotliSync() {
+  // Does this project want brotli compression?
+  const needsBrotli = config.find(row => row.compression === 'brotli')
+
+  // If it doesn't, save us the trouble.
+  if (!needsBrotli) return null
+
+  // Check if the installed version of node supports brotli
+  const hasBrotli = zlib.brotliCompressSync
+  if (hasBrotli) return nativeBrotliSync
+
+  // Looks like this version of node does not have brotli
+  // We recommend using bundlesize-plugin-brotli which acts
+  // like a polyfill
+
+  try {
+    const polyfill = require('bundlesize-plugin-brotli')
+    // if the user has installed the plugin, we can safely return it
+    return polyfill.sync
+  } catch (err) {
+    // if they haven't, show them an error and exit with error code 1
+    if (err && err.code === 'MODULE_NOT_FOUND') {
+      const message = `Missing dependency: bundlesize-plugin-brotli
+
+  To use brotli with Node versions lower than v10.16.0,
+  please install bundlesize-plugin-brotli as a dev dependency.
+
+  You can read about the compression options here:
+  https://github.com/siddharthkp/bundlesize#customisation`
+
+      error(message, { silent: true })
+    } else {
+      // if it's a different error, show the raw error
+      error(err, { silent: true })
+    }
+  }
+}
+
+function nativeBrotliSync(input) {
+  return zlib.brotliCompressSync(input).length
+}
+
+module.exports = { sync: getBrotliSync() }

src/compressed-size.js

@@ -1,5 +1,5 @@
 const gzip = require('gzip-size')
-const brotli = require('brotli-size')
+const brotli = require('./brotli')
 
 const getCompressedSize = (data, compression = 'gzip') => {
   let size