added bundle analysis

caveats:
* there might be performance implications:
  doesdev/rollup-plugin-analyzer#3
* no detailed report yet:
  doesdev/rollup-plugin-analyzer#2
* missing configuration options (cf. inline comment)

lib/bundle/bundler.js

@@ -1,11 +1,25 @@
+let rollupAnalyzer = require("rollup-plugin-analyzer").plugin;
 let rollup = require("rollup");
 
 module.exports = function generateBundle(entryPoint, target, config, cache) {
-	let { readConfig, writeConfig } = config;
+	let { readConfig, writeConfig, reporting } = config;
 	let options = Object.assign({}, readConfig, {
 		input: entryPoint,
 		cache
 	});
+
+	if(reporting) {
+		options.plugins.push(rollupAnalyzer({
+			root: reporting.referenceDir,
+			// TODO: support for options: `limit`, `filter`, `showExports`, `hideDeps`
+			onAnalysis: res => void reporting.report({
+				size: res.bundleSize,
+				originalSize: res.bundleOrigSize,
+				reduction: res.bundleReduction
+			})
+		}));
+	}
+
 	return rollup.rollup(options).
 		then(bundle => {
 			let modules = bundle.modules.reduce(collectModulePaths, new Set());

lib/bundle/index.js

@@ -4,13 +4,14 @@ let generateBundle = require("./bundler");
 let generateConfig = require("./config");
 let { generateError } = require("../util");
 let SerializedRunner = require("faucet-pipeline/lib/util/runner");
+let path = require("path");
 
 let DEFAULTS = {
 	format: "iife"
 };
 
 module.exports = class Bundle {
-	constructor(entryPoint, target, config, { browsers, resolvePath }) {
+	constructor(entryPoint, target, config, { browsers, referenceDir, resolvePath }) {
 		this.entryPoint = entryPoint;
 		this.target = target;
 
@@ -20,6 +21,27 @@ module.exports = class Bundle {
 			delete config.fingerprint;
 		}
 		this._config = generateConfig(config, { browsers, resolvePath });
+
+		let { reporting } = config;
+		if(reporting !== false) {
+			reporting = reporting || {};
+			let threshold = reporting.threshold || 100000; // ~100 kB
+			this._config.reporting = {
+				referenceDir,
+				report: ({ size, originalSize, reduction }) => {
+					let b2kb = i => `${Math.round(i / 1024)} kB`;
+					console.error(`${b2kb(originalSize)} → ${b2kb(size)} ` +
+							`(Δ ${Math.round(reduction)} %)`);
+					if(size > threshold) {
+						console.error("⚠️ this bundle looks to be fairly big - " +
+								"you might want to double-check whether " +
+								"that's intended and consider performance " +
+								"implications for your users: " +
+								path.relative(referenceDir, target));
+					}
+				}
+			};
+		}
 	}
 
 	// recompiles the bundle if its dependency graph includes any of the given files

lib/index.js

@@ -2,13 +2,12 @@
 
 let Bundle = require("./bundle");
 let { abort, repr } = require("faucet-pipeline/lib/util");
-let path = require("path");
 
 module.exports = (config, assetManager, { watcher, browsers, compact } = {}) => {
 	let bundles = config.map(bundleConfig => {
 		// NB: bundle-specific configuration can override global options
 		bundleConfig = Object.assign({ compact }, bundleConfig);
-		return makeBundle(bundleConfig, assetManager.resolvePath, { browsers });
+		return makeBundle(bundleConfig, assetManager, { browsers });
 	});
 
 	let res = bundles.map(bundle => {
@@ -38,13 +37,6 @@ module.exports = (config, assetManager, { watcher, browsers, compact } = {}) =>
 
 function makeWriter(bundle, assetManager, { fingerprint } = {}) {
 	return ({ code, error }) => {
-		if(code.length > 100000) { // ~100 kB -- XXX: arbitrary -- TODO: configurable
-			console.error("⚠️ this bundle looks to be fairly big, you might " +
-					"want to double-check whether that's intended and " +
-					"consider performance implications for your users:\n  " +
-					path.relative(assetManager.referenceDir, bundle.target));
-		}
-
 		let options = { error };
 		if(fingerprint !== undefined) {
 			options.fingerprint = fingerprint;
@@ -53,7 +45,7 @@ function makeWriter(bundle, assetManager, { fingerprint } = {}) {
 	};
 }
 
-function makeBundle(config, resolvePath, { browsers }) {
+function makeBundle(config, { referenceDir, resolvePath }, { browsers }) {
 	// dissect configuration for constructor
 	config = Object.assign({}, config);
 	let [entryPoint, target] = extract(config, "source", "target");
@@ -64,7 +56,8 @@ function makeBundle(config, resolvePath, { browsers }) {
 
 	entryPoint = resolvePath(entryPoint);
 	target = resolvePath(target, { enforceRelative: true });
-	return new Bundle(entryPoint, target, config, { browsers, resolvePath });
+	return new Bundle(entryPoint, target, config,
+			{ browsers, referenceDir, resolvePath });
 }
 
 // removes properties from object, returning their respective values

package.json

@@ -28,6 +28,7 @@
 	"dependencies": {
 		"faucet-pipeline": "~1.0.0-rc.7",
 		"rollup": "~0.62.0",
+		"rollup-plugin-analyzer": "^2.0.4",
 		"rollup-plugin-cleanup": "~3.0.0",
 		"rollup-plugin-commonjs": "~9.1.3",
 		"rollup-plugin-node-resolve": "~3.3.0"

test/cli/test_custom_config/assets.js

@@ -5,7 +5,10 @@ let path = require("path");
 module.exports = {
 	js: [{
 		source: "./index.js",
-		target: "./dist/bundle.js"
+		target: "./dist/bundle.js",
+		reporting: {
+			threshold: 100
+		}
 	}],
 	plugins: {
 		js: path.resolve(__dirname, "../../..")

test/cli/test_custom_config/expected.js

@@ -5,6 +5,22 @@ if(typeof global === "undefined" && typeof window !== "undefined") {
 	window.global = window;
 }
 
-// N/A
+// lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
+// tempor incididunt ut labore et dolore magna aliqua
+// ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut
+// aliquip ex ea commodo consequat
+// duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore
+// eu fugiat nulla pariatur
+// excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia
+// deserunt mollit anim id est laborum
+//
+// lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
+// tempor incididunt ut labore et dolore magna aliqua
+// ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut
+// aliquip ex ea commodo consequat
+// duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore
+// eu fugiat nulla pariatur
+// excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia
+// deserunt mollit anim id est laborum
 
 }());

test/cli/test_custom_config/index.js

@@ -1 +1,17 @@
-// N/A
+// lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
+// tempor incididunt ut labore et dolore magna aliqua
+// ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut
+// aliquip ex ea commodo consequat
+// duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore
+// eu fugiat nulla pariatur
+// excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia
+// deserunt mollit anim id est laborum
+//
+// lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
+// tempor incididunt ut labore et dolore magna aliqua
+// ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut
+// aliquip ex ea commodo consequat
+// duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore
+// eu fugiat nulla pariatur
+// excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia
+// deserunt mollit anim id est laborum