test: add e2e tests for css modules (#693)

This PR relates to #186. It adds e2e tests for CSS modules.
I used `expect .toContain('class-name')` because I was not sure if the
generated name would always be the same.

---------

Co-authored-by: ¨Leonardo <¨[email protected]¨>
Co-authored-by: Daishi Kato <[email protected]>

e2e/fixtures/rsc-css-modules/README.md

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+# RSC CSS Modules
+
+Only RSC features, no SSR. Using css modules to style the application, both on server and client components.

e2e/fixtures/rsc-css-modules/declaration.d.ts

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+declare module '*.module.css';

e2e/fixtures/rsc-css-modules/package.json

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+{
+  "name": "rsc-css-modules",
+  "version": "0.1.0",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "dev": "waku dev",
+    "build": "waku build",
+    "start": "waku start"
+  },
+  "dependencies": {
+    "react": "19.0.0-beta-4508873393-20240430",
+    "react-dom": "19.0.0-beta-4508873393-20240430",
+    "react-server-dom-webpack": "19.0.0-beta-4508873393-20240430",
+    "waku": "workspace:*"
+  },
+  "devDependencies": {
+    "@types/react": "18.3.1",
+    "@types/react-dom": "18.3.0",
+    "typescript": "5.4.4"
+  }
+}

e2e/fixtures/rsc-css-modules/src/components/App.tsx

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+import styles from './app.module.css';
+import { ClientCounter } from './ClientCounter.js';
+
+const App = ({ name }: { name: string }) => {
+  return (
+    <div data-testid="app-wrapper" className={styles.wrapper}>
+      <title>Waku example</title>
+      <p className={styles.text} data-testid="app-name">
+        {name}
+      </p>
+      <ClientCounter />
+    </div>
+  );
+};
+
+export default App;

e2e/fixtures/rsc-css-modules/src/components/ClientCounter.tsx

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+'use client';
+import { useState } from 'react';
+import styles from './clientCounter.module.css';
+
+export const ClientCounter = () => {
+  const [count, setCount] = useState(0);
+
+  return (
+    <div className={styles.counterWrapper} data-testid="client-counter">
+      <p data-testid="count">{count}</p>
+      <button
+        className={styles.counterButton}
+        data-testid="increment"
+        onClick={() => setCount((c) => c + 1)}
+      >
+        Increment
+      </button>
+    </div>
+  );
+};

e2e/fixtures/rsc-css-modules/src/components/app.module.css

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+.wrapper {
+  display: flex;
+  flex-direction: column;
+}
+
+.text {
+  font-size: 18px;
+  color: blue;
+}

e2e/fixtures/rsc-css-modules/src/components/clientCounter.module.css

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+.counterWrapper {
+  display: flex;
+  flex-direction: row;
+  gap: 4px;
+}
+
+.counterButton {
+  padding: 8px;
+}

e2e/fixtures/rsc-css-modules/src/entries.tsx

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+import { lazy } from 'react';
+import { defineEntries } from 'waku/server';
+
+const App = lazy(() => import('./components/App.js'));
+
+export default defineEntries(
+  // renderEntries
+  async (input) => {
+    return {
+      App: <App name={input || 'Waku'} />,
+    };
+  },
+  // getBuildConfig
+  async () => [{ pathname: '/', entries: [{ input: '' }] }],
+  // getSsrConfig
+  () => {
+    throw new Error('SSR should not be used in this test.');
+  },
+);

e2e/fixtures/rsc-css-modules/src/main.tsx

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+import { StrictMode } from 'react';
+import { createRoot } from 'react-dom/client';
+import { Root, Slot } from 'waku/client';
+
+const rootElement = (
+  <StrictMode>
+    <Root>
+      <Slot id="App" />
+    </Root>
+  </StrictMode>
+);
+
+createRoot(document.body).render(rootElement);

e2e/fixtures/rsc-css-modules/tsconfig.json

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+{
+  "compilerOptions": {
+    "strict": true,
+    "target": "esnext",
+    "downlevelIteration": true,
+    "esModuleInterop": true,
+    "module": "nodenext",
+    "skipLibCheck": true,
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+    "types": ["react/experimental"],
+    "jsx": "react-jsx",
+    "outDir": "./dist",
+    "composite": true
+  },
+  "include": ["./src", "./waku.config.ts", "declaration.d.ts"]
+}

e2e/fixtures/rsc-css-modules/waku.config.ts

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+const DO_NOT_BUNDLE = '';
+
+/** @type {import('waku/config').Config} */
+export default {
+  middleware: (cmd: 'dev' | 'start') => [
+    ...(cmd === 'dev'
+      ? [
+          import(
+            /* @vite-ignore */ DO_NOT_BUNDLE + 'waku/middleware/dev-server'
+          ),
+        ]
+      : []),
+    import('waku/middleware/rsc'),
+    import('waku/middleware/fallback'),
+  ],
+};

e2e/rsc-css-modules.spec.ts

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+import { expect } from '@playwright/test';
+import { execSync, exec, ChildProcess } from 'node:child_process';
+import { fileURLToPath } from 'node:url';
+import waitPort from 'wait-port';
+import { debugChildProcess, getFreePort, terminate, test } from './utils.js';
+import { rm } from 'node:fs/promises';
+
+const waku = fileURLToPath(
+  new URL('../packages/waku/dist/cli.js', import.meta.url),
+);
+
+const commands = [
+  {
+    command: 'dev',
+  },
+  {
+    build: 'build',
+    command: 'start',
+  },
+];
+
+const cwd = fileURLToPath(
+  new URL('./fixtures/rsc-css-modules', import.meta.url),
+);
+
+for (const { build, command } of commands) {
+  test.describe(`rsc-css-modules: ${command}`, () => {
+    let cp: ChildProcess;
+    let port: number;
+    test.beforeAll('remove cache', async () => {
+      await rm(`${cwd}/dist`, {
+        recursive: true,
+        force: true,
+      });
+    });
+
+    test.beforeAll(async () => {
+      if (build) {
+        execSync(`node ${waku} ${build}`, { cwd });
+      }
+      port = await getFreePort();
+      cp = exec(`node ${waku} ${command} --port ${port}`, { cwd });
+      debugChildProcess(cp, fileURLToPath(import.meta.url), [
+        /ExperimentalWarning: Custom ESM Loaders is an experimental feature and might change at any time/,
+      ]);
+      await waitPort({ port });
+    });
+
+    test.afterAll(async () => {
+      await terminate(cp.pid!);
+    });
+
+    test('css-modules classes', async ({ page }) => {
+      await page.goto(`http://localhost:${port}/`);
+
+      const wrapperClass = await page
+        .getByTestId('app-wrapper')
+        .getAttribute('class');
+      expect(wrapperClass).toContain('wrapper');
+
+      const appNameClass = await page
+        .getByTestId('app-name')
+        .getAttribute('class');
+      expect(appNameClass).toContain('text');
+
+      const clientcounterClass = await page
+        .getByTestId('client-counter')
+        .getAttribute('class');
+      expect(clientcounterClass).toContain('counterWrapper');
+
+      const incrementClass = await page
+        .getByTestId('increment')
+        .getAttribute('class');
+      expect(incrementClass).toContain('counterButton');
+    });
+  });
+}

tsconfig.e2e.json

@@ -9,6 +9,9 @@
     {
       "path": "./e2e/fixtures/rsc-basic/tsconfig.json"
     },
+    {
+      "path": "./e2e/fixtures/rsc-css-modules/tsconfig.json"
+    },
     {
       "path": "./e2e/fixtures/ssr-basic/tsconfig.json"
     },