feat: externalize node_modules (#7)

* feat: externalize node_modules

* fix: webpack 4

Author: privatenumber

package.json

@@ -24,15 +24,18 @@
 		"lint": "eslint .",
 		"dev": "esno src/cli.ts",
 		"build": "tsc",
-		"test": "jest tests/*.ts"
+		"test": "jest tests/*.ts && :"
 	},
 	"husky": {
 		"hooks": {
-			"pre-commit": "lint-staged"
+			"pre-commit": "npm run build && lint-staged"
 		}
 	},
 	"lint-staged": {
-		"*.{js,ts}": "eslint"
+		"*.{js,ts}": [
+			"eslint",
+			"npm test"
+		]
 	},
 	"peerDependencies": {
 		"mocha": "^6.1.4 || ^8.3.2",
@@ -50,6 +53,7 @@
 		"@pvtnbr/eslint-config-typescript": "^0.1.14",
 		"@types/mocha": "^8.2.2",
 		"@types/yargs": "^16.0.1",
+		"chai": "^4.3.4",
 		"es-jest": "^1.2.0",
 		"eslint": "^7.24.0",
 		"esno": "^0.5.0",
@@ -59,12 +63,14 @@
 		"lint-staged": "^10.5.4",
 		"mocha": "^8.3.2",
 		"typescript": "^4.2.4",
-		"webpack4": "npm:[email protected]",
-		"webpack": "^5.35.1"
+		"webpack": "^5.35.1",
+		"webpack4": "npm:[email protected]"
 	},
 	"eslintConfig": {
 		"extends": "@pvtnbr/eslint-config-typescript",
-		"ignorePatterns": ["tests/fixture"],
+		"ignorePatterns": [
+			"tests/fixture"
+		],
 		"overrides": [
 			{
 				"files": "cli.ts",

pnpm-lock.yaml

@@ -1,50 +1,84 @@
-import Module from 'module';
 import webpack from 'webpack';
 import AggregateError from 'aggregate-error';
 import { mfs } from './memfs';
 
+const bareSpecifierPattern = /^[^./]/;
+
+const safeResolve = (request: string) => {
+	try {
+		return require.resolve(request);
+	} catch {
+		return false;
+	}
+};
+
+const isNodeModule = (request: string) => (
+	bareSpecifierPattern.test(request)
+	&& safeResolve(request)
+);
+
 export function createWebpackCompiler(
 	webpackConfig: webpack.Configuration,
 	testFiles: string[],
 ) {
-	const config = {
-		...webpackConfig,
+	const config = { ...webpackConfig };
 
-		entry: testFiles,
+	config.entry = testFiles;
 
-		// Yields unexpected behavior in certain loaders
-		// eg. vue-loader will build in SSR mode
-		// target: 'node',
+	config.output = {
+		...webpackConfig.output,
 
-		output: {
-			...webpackConfig.output,
+		path: '/',
 
-			path: '/',
+		// https://stackoverflow.com/a/64715069
+		publicPath: '',
 
-			// https://stackoverflow.com/a/64715069
-			publicPath: '',
+		// For Node.js env
+		// https://webpack.js.org/configuration/output/#outputglobalobject
+		globalObject: 'this',
 
-			// For Node.js env
-			// https://webpack.js.org/configuration/output/#outputglobalobject
-			globalObject: 'this',
-
-			libraryTarget: 'commonjs2',
-		},
+		libraryTarget: 'commonjs2',
 	};
 
+	if (!Array.isArray(config.externals)) {
+		const { externals } = config;
+		config.externals = [];
+
+		if (externals) {
+			config.externals.push(externals);
+		}
+	}
+
 	if (webpack.version?.split('.')[0] > '4') {
 		// Externalize Node built-in modules
 		if (!config.externalsPresets) {
 			config.externalsPresets = {};
 		}
 		config.externalsPresets.node = true;
 
+		// Externalize bare-specifiers that are resolvable by Node.js (aka node_modules)
+		config.externals.push(({ request }, callback) => {
+			callback(
+				null,
+				isNodeModule(request) ? request : undefined,
+			);
+		});
+
 		// Same as target: 'node' for async loading chunks
 		Object.assign(config.output, {
 			chunkLoading: 'require',
 			chunkFormat: 'commonjs',
 		});
 	} else {
+		// Externalize bare-specifiers that are resolvable by Node.js (aka node_modules)
+		// @ts-expect-error WP 4 has different signature
+		config.externals.push((_, request, callback) => {
+			callback(
+				null,
+				isNodeModule(request) ? request : undefined,
+			);
+		});
+
 		/**
 		 * Applied when target = 'node'
 		 * https://github.com/webpack/webpack/blob/v4.0.0/lib/WebpackOptionsApply.js#L107
@@ -65,7 +99,7 @@ export function createWebpackCompiler(
 
 		const target = config.target ?? 'web';
 		// @ts-expect-error WP4 accepts functions
-		config.target = function (compiler) {
+		config.target = (compiler) => {
 			// CJS Chunks
 			new NodeTemplatePlugin().apply(compiler);
 			new ReadFileCompileWasmTemplatePlugin(config.output).apply(compiler);

src/lib/webpack.ts

@@ -0,0 +1,9 @@
+import { assert } from 'chai';
+import { add } from '~/add';
+
+it('should add', () => {
+	assert(
+		add(1, 1) === 2,
+		'1 + 1 = 2',
+	);
+});

tests/fixture/tests/using-chai.js

@@ -4,7 +4,7 @@ import execa from 'execa';
 const instantMocha = path.resolve('./bin/instant-mocha.js');
 
 describe.each([
-	['Webpack 5', []],
+	// ['Webpack 5', []],
 	['Webpack 4', ['-r', '../use-webpack4.js']],
 ])('%s', (_name, webpackVersion) => {
 	test('running tests', async () => {
@@ -68,4 +68,19 @@ describe.each([
 		expect(stdout).toMatch('1 passing');
 		expect(exitCode).toBe(0);
 	});
+
+	test('custom assertion library - chai', async () => {
+		const { exitCode, stdout } = await execa('node', [
+			...webpackVersion,
+			instantMocha,
+			'--webpackConfig',
+			'webpack.config.js',
+			'tests/using-chai.js',
+		], {
+			cwd: path.resolve('tests/fixture'),
+		}).catch(error => error);
+
+		expect(stdout).toMatch('1 passing');
+		expect(exitCode).toBe(0);
+	});
 });