Implement browserslist handling outside of core

lib/index.js

@@ -1,4 +1,4 @@
-let { abort } = require("faucet-pipeline-core/lib/util");
+let { abort, repr } = require("faucet-pipeline-core/lib/util");
 let makeAutoprefixer = require("./make-autoprefixer");
 let makeSassRenderer = require("./make-sass-renderer");
 
@@ -8,14 +8,14 @@
 	plugin: faucetSass
 };
 
-function faucetSass(config, assetManager, { browsers, compact, sourcemaps } = {}) {
+function faucetSass(config, assetManager, { compact, sourcemaps } = {}) {
 	let bundlers = config.map(bundleConfig =>
-		makeBundler(bundleConfig, assetManager, { browsers, compact, sourcemaps }));
+		makeBundler(bundleConfig, assetManager, { compact, sourcemaps }));
 
 	return filepaths => Promise.all(bundlers.map(bundle => bundle(filepaths)));
 }
 
-function makeBundler(config, assetManager, { browsers, compact, sourcemaps } = {}) {
+function makeBundler(config, assetManager, { compact, sourcemaps } = {}) {
 	let { browserslist, fingerprint } = config;
 
 	if(!config.source || !config.target) {
@@ -25,13 +25,7 @@
 	let source = assetManager.resolvePath(config.source);
 	let target = assetManager.resolvePath(config.target, { enforceRelative: true });
 
-	if(browserslist === false) {
-		browsers = null;
-	} else if(browserslist) {
-		browsers = browsers[browserslist];
-	} else {
-		browsers = browsers.defaults;
-	}
+	let browsers = determineBrowsers(browserslist, assetManager.referenceDir);
 
 	let renderSass = makeSassRenderer(source, target, assetManager, sourcemaps, compact);
 	let autoprefix = makeAutoprefixer(source, assetManager, sourcemaps, browsers);
@@ -66,6 +60,24 @@
 	};
 }
 
+function determineBrowsers(browserslistEnv, referenceDir) {
+	if(browserslistEnv === false) {
+		return null;
+	}
+
+	let browserslist = require("browserslist");
+	let browsers = browserslist.findConfig(referenceDir) || {};
+
+	if(browserslistEnv) {
+		if(!browsers[browserslistEnv]) {
+			abort(`ERROR: The browserslist environment ${repr(browserslistEnv)} you requested is not defined`);
+		}
+		return browsers[browserslistEnv];
+	}
+
+	return browsers.defaults;
+}
+
 function previouslyIncluded(filepaths, previouslyIncludedFiles) {
 	return previouslyIncludedFiles === undefined ||
 		filepaths.some(filepath => previouslyIncludedFiles.

lib/make-sass-renderer.js

@@ -3,7 +3,7 @@ let sass = require("sass");
 module.exports = function(inputFileName, target, assetManager, sourcemaps, compact) {
 	let sassOptions = {
 		style: compact ? "compressed" : "expanded",
-		loadPaths: [assetManager.packagesDir],
+		loadPaths: [assetManager.resolvePath("./node_modules")],
 		sourceMap: sourcemaps,
 		functions: {
 			"asset-url($assetName)": args => {

package.json

@@ -23,6 +23,7 @@
 	},
 	"dependencies": {
 		"autoprefixer": "~10.4.20",
+		"browserslist": "^4.24.4",
 		"faucet-pipeline-core": "^2.0.0 || ^3.0.0",
 		"postcss": "~8.5.1",
 		"sass": "~1.86.0"

test/test_prefix_with_different_browserslist/.browserslistrc

@@ -1,5 +1,4 @@
-[default]
 chrome 64
 
-[development]
+[legacy]
 IE 10

test/test_prefix_with_different_browserslist/faucet.config.js

@@ -5,7 +5,7 @@ module.exports = {
 	sass: [{
 		source: "./src/index.scss",
 		target: "./dist/bundle.css",
-		browserslist: "development"
+		browserslist: "legacy"
 	}],
 	manifest: {
 		target: "./dist/manifest.json",