refactor: Determine CSS module by filename, not directory (#1714)

* refactor: Determine CSS module by filename, not directory

* docs: Adding changeset

* refactor: Project creation pull from templates 'main' branch

* test: Updating tests

* revert: Accidentally removed log message

Author: rschristian

.changeset/cyan-tomatoes-count.md

@@ -0,0 +1,11 @@
+---
+'preact-cli': major
+---
+
+Alters CSS Module detection to instead rely upon file names, rather than directory names.
+
+Treating all CSS files found within `routes/` and `components/` as CSS Modules was not obvious, nor did it offer an easy way to opt out (or in) without editing the Webpack config itself.
+
+This change makes is so that users can opt into CSS Modules from anywhere in their app by instead naming their CSS files according to the pattern `*.module.css`.
+
+Anyone using CSS Modules within `routes/` or `components/` will need to alter their CSS files to be `x.module.css`. If you've disabled CSS Modules in your `preact.config.js`, you can remove that bit of configuration and use file names to instead determine behavior.

packages/cli/global.d.ts

@@ -15,3 +15,16 @@ declare module 'shelljs' {
 	};
 	export = shell;
 }
+
+declare module '*.module.css' {
+	const classes: { [key: string]: string };
+	export default classes;
+}
+declare module '*.module.sass' {
+	const classes: { [key: string]: string };
+	export default classes;
+}
+declare module '*.module.scss' {
+	const classes: { [key: string]: string };
+	export default classes;
+}

packages/cli/src/commands/create.js

@@ -221,6 +221,11 @@ exports.create = async function createCommand(repo, dest, argv) {
 	if (!repo.includes('/')) {
 		repo = `${ORG}/${repo}`;
 		info(`Assuming you meant ${repo}...`);
+
+		// TODO: Remove this after updating all templates
+		if (repo.endsWith('default') || repo.endsWith('typescript')) {
+			repo += '#next';
+		}
 	}
 
 	if (!existsSync(resolve(cwd, dest, 'src'))) {

packages/cli/src/lib/webpack/run-webpack.js

@@ -142,7 +142,7 @@ function writeJsonStats(cwd, stats) {
 function allFields(stats, field, fields = [], name = null) {
 	const info = stats.toJson({
 		errors: true,
-		warnings: false,
+		warnings: true,
 		errorDetails: false,
 	});
 	const addCompilerPrefix = msg =>

packages/cli/src/lib/webpack/webpack-base-config.js

@@ -49,7 +49,7 @@ function resolveTsconfig(cwd, isProd) {
  * @returns {import('webpack').Configuration}
  */
 module.exports = function createBaseConfig(env) {
-	const { cwd, isProd, isWatch, src, source } = env;
+	const { cwd, isProd, src, source } = env;
 	const IS_SOURCE_PREACT_X_OR_ABOVE = isInstalledVersionPreactXOrAbove(cwd);
 	// Apply base-level `env` values
 	env.dest = resolve(cwd, env.dest || 'build');
@@ -214,20 +214,15 @@ module.exports = function createBaseConfig(env) {
 					],
 				},
 				{
-					// User styles
 					test: /\.(p?css|less|s[ac]ss|styl)$/,
-					include: [source('components'), source('routes')],
+					exclude: /\.module\.(p?css|less|s[ac]ss|styl)$/,
 					use: [
-						isWatch
-							? require.resolve('style-loader')
-							: MiniCssExtractPlugin.loader,
+						isProd
+							? MiniCssExtractPlugin.loader
+							: require.resolve('style-loader'),
 						{
 							loader: require.resolve('css-loader'),
 							options: {
-								modules: {
-									localIdentName: '[local]__[hash:base64:5]',
-								},
-								importLoaders: 1,
 								sourceMap: true,
 							},
 						},
@@ -241,18 +236,25 @@ module.exports = function createBaseConfig(env) {
 							},
 						},
 					],
+					// Don't consider CSS imports dead code even if the
+					// containing package claims to have no side effects.
+					// Remove this when webpack adds a warning or an error for this.
+					// See https://github.com/webpack/webpack/issues/6571
+					sideEffects: true,
 				},
 				{
-					// External / `node_module` styles
-					test: /\.(p?css|less|s[ac]ss|styl)$/,
-					exclude: [source('components'), source('routes')],
+					test: /\.module\.(p?css|less|s[ac]ss|styl)$/,
 					use: [
-						isWatch
-							? require.resolve('style-loader')
-							: MiniCssExtractPlugin.loader,
+						isProd
+							? MiniCssExtractPlugin.loader
+							: require.resolve('style-loader'),
 						{
 							loader: require.resolve('css-loader'),
 							options: {
+								modules: {
+									localIdentName: '[local]__[hash:base64:5]',
+								},
+								importLoaders: 1,
 								sourceMap: true,
 							},
 						},
@@ -266,11 +268,6 @@ module.exports = function createBaseConfig(env) {
 							},
 						},
 					],
-					// Don't consider CSS imports dead code even if the
-					// containing package claims to have no side effects.
-					// Remove this when webpack adds a warning or an error for this.
-					// See https://github.com/webpack/webpack/issues/6571
-					sideEffects: true,
 				},
 				{
 					test: /\.(xml|html|txt|md)$/,
@@ -349,7 +346,7 @@ module.exports = function createBaseConfig(env) {
 
 		mode: isProd ? 'production' : 'development',
 
-		devtool: isWatch ? 'eval-cheap-module-source-map' : 'source-map',
+		devtool: isProd ? 'source-map' : 'eval-cheap-module-source-map',
 
 		node: {
 			__filename: false,

packages/cli/tests/build.test.js

@@ -177,7 +177,9 @@ describe('preact build', () => {
 			await rename(join(dir, 'index.js'), join(dir, 'renamed-src/index.js'));
 			await rename(join(dir, 'style.css'), join(dir, 'renamed-src/style.css'));
 
-			await expect(buildFast(dir, { src: 'renamed-src' })).resolves.not.toThrow();
+			await expect(
+				buildFast(dir, { src: 'renamed-src' })
+			).resolves.not.toThrow();
 		});
 
 		it('--dest', async () => {
@@ -361,18 +363,13 @@ describe('preact build', () => {
 			expect(builtStylesheet).toMatch('h2{color:green}');
 		});
 
-		it('should use CSS Modules in `routes` and `components` directories', async () => {
-			let dir = await subject('css-auto-modules');
+		it('should use plain CSS & CSS Modules together, determining loading method by filename', async () => {
+			let dir = await subject('css-modules');
 			await buildFast(dir);
 			const builtStylesheet = await getOutputFile(dir, /bundle\.\w{5}\.css$/);
-			const builtSplitStylesheet = await getOutputFile(
-				dir,
-				/route-index\.chunk\.\w{5}\.css$/
-			);
 
 			expect(builtStylesheet).toMatch('h1{color:red}');
-			expect(builtStylesheet).toMatch(/\.text__\w{5}{color:tan}/);
-			expect(builtSplitStylesheet).toMatch(/\.text__\w{5}{color:red}/);
+			expect(builtStylesheet).toMatch(/\.text__\w{5}{color:blue}/);
 		});
 
 		it('should inline critical CSS only', async () => {
@@ -394,12 +391,14 @@ describe('preact build', () => {
 			expect(builtStylesheet).toMatch('h1{background:#673ab8}');
 		});
 
-		it('should use SASS styles', async () => {
+		it('should use SASS, SCSS, and CSS Modules for each', async () => {
 			let dir = await subject('css-sass');
 			await buildFast(dir);
+			const builtStylesheet = await getOutputFile(dir, /bundle\.\w{5}\.css$/);
 
-			let body = await getBody(dir);
-			looksLike(body, images.sass);
+			expect(builtStylesheet).toMatch('h1{background:blue;color:red}');
+			expect(builtStylesheet).toMatch(/\.text__\w{5}{color:blue}/);
+			expect(builtStylesheet).toMatch(/\.text__\w{5}{background:red}/);
 		});
 	});
 

packages/cli/tests/images/build.js

@@ -46,16 +46,6 @@ exports.default = {
 	'route-profile.chunk.4de97.legacy.js.map': 15421,
 };
 
-exports.sass = `
-<body>
-	<div class="background__sL1ip">
-		<h1>Header on background</h1>
-		<p>Paragraph on background</p>
-	</div>
-	{{ ... }}
-</body>
-`;
-
 exports.prerender = {};
 
 exports.prerender.heads = {};

packages/cli/tests/images/create.js

@@ -15,11 +15,11 @@ exports.default = [
 	'src/assets/preact-logo.svg',
 	'src/components/app.js',
 	'src/components/header/index.js',
-	'src/components/header/style.css',
+	'src/components/header/style.module.css',
 	'src/index.js',
 	'src/manifest.json',
 	'src/routes/home/index.js',
-	'src/routes/home/style.css',
+	'src/routes/home/style.module.css',
 	'src/routes/profile/index.js',
 	'src/style/index.css',
 	'src/sw.js',