feat(browser): support Locator and Assertion

e2e/browser-mode/fixtures/locator-api/rstest.config.ts

@@ -0,0 +1,13 @@
+import { defineConfig } from '@rstest/core';
+import { BROWSER_PORTS } from '../ports';
+
+export default defineConfig({
+  browser: {
+    enabled: true,
+    provider: 'playwright',
+    headless: true,
+    port: BROWSER_PORTS['locator-api'],
+  },
+  include: ['tests/**/*.test.ts'],
+  testTimeout: 30000,
+});

e2e/browser-mode/fixtures/locator-api/tests/locatorApi.test.ts

@@ -0,0 +1,129 @@
+import { page } from '@rstest/browser';
+import { expect, test } from '@rstest/core';
+
+function createCounter(initial = 0) {
+  let count = initial;
+
+  const container = document.createElement('div');
+  const display = document.createElement('p');
+  const incBtn = document.createElement('button');
+
+  display.textContent = `Count: ${count}`;
+  incBtn.textContent = 'Increment';
+  incBtn.id = 'inc-btn';
+
+  incBtn.addEventListener('click', () => {
+    count++;
+    display.textContent = `Count: ${count}`;
+  });
+
+  container.append(display, incBtn);
+  return container;
+}
+
+test('locator + expect.element proxy works', async () => {
+  document.body.appendChild(createCounter(5));
+
+  const nameInput = document.createElement('input');
+  nameInput.placeholder = 'Name';
+
+  const emailInput = document.createElement('input');
+  emailInput.placeholder = 'Email';
+
+  document.body.append(nameInput, emailInput);
+
+  const sections = document.createElement('div');
+  sections.innerHTML = `
+    <section>
+      <h2>Home</h2>
+      <button>Save</button>
+    </section>
+    <section>
+      <h2>Profile</h2>
+      <button>Save</button>
+    </section>
+  `;
+  document.body.append(sections);
+
+  await expect.element(page.getByText('Count: 5')).toBeVisible();
+  await page.getByRole('button', { name: 'Increment' }).click();
+  await expect.element(page.getByText('Count: 6')).toBeVisible();
+  await expect.element(page.getByText('Count: 6')).toHaveText('Count: 6');
+  await expect
+    .element(page.getByRole('button', { name: 'Increment' }))
+    .toHaveId('inc-btn');
+
+  await page.getByPlaceholder('Name').fill('Alice');
+  await expect.element(page.getByPlaceholder('Name')).toHaveValue('Alice');
+
+  await page.getByPlaceholder('Email').fill('a@b.com');
+  await expect.element(page.getByPlaceholder('Email')).toHaveValue('a@b.com');
+
+  // filter({ has })
+  const profileSave = page
+    .locator('section')
+    .filter({ has: page.getByRole('heading', { name: 'Profile' }) })
+    .getByRole('button', { name: 'Save' });
+  await expect.element(profileSave).toHaveCount(1, { timeout: 1000 });
+
+  const checkbox = document.createElement('input');
+  checkbox.type = 'checkbox';
+  checkbox.id = 'agree';
+
+  const label = document.createElement('label');
+  label.htmlFor = 'agree';
+  label.textContent = 'Agree';
+
+  document.body.append(checkbox, label);
+
+  await expect.element(page.getByLabel('Agree')).toBeUnchecked();
+  await page.getByLabel('Agree').check();
+  await expect.element(page.getByLabel('Agree')).toBeChecked();
+  await expect.element(page.getByLabel('Agree')).not.toBeUnchecked();
+  await page.getByLabel('Agree').uncheck();
+  await expect.element(page.getByLabel('Agree')).toBeUnchecked();
+  await expect.element(page.getByLabel('Agree')).not.toBeChecked();
+
+  await page.getByLabel('Agree').focus();
+  await expect.element(page.getByLabel('Agree')).toBeFocused();
+
+  // selectOption
+  const selectLabel = document.createElement('label');
+  selectLabel.htmlFor = 'choice';
+  selectLabel.textContent = 'Choice';
+
+  const select = document.createElement('select');
+  select.id = 'choice';
+  select.innerHTML = `
+    <option value="a">A</option>
+    <option value="b">B</option>
+  `;
+  document.body.append(selectLabel, select);
+  await page.getByLabel('Choice').selectOption('b');
+  await expect.element(page.getByLabel('Choice')).toHaveValue('b');
+
+  // toBeAttached/toBeDetached
+  const later = document.createElement('div');
+  later.id = 'later';
+  setTimeout(() => document.body.appendChild(later), 50);
+  await expect.element(page.locator('#later')).toBeAttached();
+  later.remove();
+  await expect.element(page.locator('#later')).toBeDetached();
+
+  // dispatchEvent
+  const evBtn = document.createElement('button');
+  evBtn.textContent = 'Event';
+  evBtn.addEventListener('custom', () => {
+    evBtn.textContent = 'Event:OK';
+  });
+  document.body.appendChild(evBtn);
+  await page.getByRole('button', { name: 'Event' }).dispatchEvent('custom');
+  await expect.element(page.getByText('Event:OK')).toBeVisible();
+
+  // and/or composition
+  const incBtn = page.getByRole('button', { name: 'Increment' });
+  await expect.element(incBtn.and(page.locator('#inc-btn'))).toHaveCount(1);
+  await expect
+    .element(page.getByPlaceholder('Name').or(page.getByPlaceholder('Email')))
+    .toHaveCount(2);
+});

e2e/browser-mode/fixtures/multi-project-config/project-a/rstest.config.ts

@@ -0,0 +1,12 @@
+import { pluginReact } from '@rsbuild/plugin-react';
+import { defineConfig } from '@rstest/core';
+
+export default defineConfig({
+  name: 'project-a',
+  plugins: [pluginReact()],
+  include: ['tests/**/*.test.tsx'],
+  browser: {
+    enabled: true,
+    provider: 'playwright',
+  },
+});

e2e/browser-mode/fixtures/multi-project-config/project-a/tests/jsxRuntime.test.tsx

@@ -0,0 +1,6 @@
+import { expect, test } from '@rstest/core';
+
+test('jsx runtime works without React in scope', () => {
+  const element = <span>hello</span>;
+  expect(element.props.children).toBe('hello');
+});

e2e/browser-mode/fixtures/multi-project-config/project-a/tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "lib": ["ES2020", "DOM"],
+    "module": "ESNext",
+    "strict": true,
+    "skipLibCheck": true,
+    "isolatedModules": true,
+    "resolveJsonModule": true,
+    "moduleResolution": "bundler",
+    "jsx": "react-jsx",
+    "types": ["@rstest/core"]
+  },
+  "include": ["tests", "rstest.config.ts"]
+}

e2e/browser-mode/fixtures/multi-project-config/project-b/rstest.config.ts

@@ -0,0 +1,10 @@
+import { defineConfig } from '@rstest/core';
+
+export default defineConfig({
+  name: 'project-b',
+  include: ['tests/**/*.test.ts'],
+  browser: {
+    enabled: true,
+    provider: 'playwright',
+  },
+});

e2e/browser-mode/fixtures/multi-project-config/project-b/tests/smoke.test.ts

@@ -0,0 +1,5 @@
+import { expect, test } from '@rstest/core';
+
+test('smoke', () => {
+  expect(1 + 1).toBe(2);
+});

e2e/browser-mode/fixtures/multi-project-config/project-b/tsconfig.json

@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "lib": ["ES2020", "DOM"],
+    "module": "ESNext",
+    "strict": true,
+    "skipLibCheck": true,
+    "isolatedModules": true,
+    "resolveJsonModule": true,
+    "moduleResolution": "bundler",
+    "types": ["@rstest/core"]
+  },
+  "include": ["tests", "rstest.config.ts"]
+}

e2e/browser-mode/fixtures/multi-project-config/rstest.config.ts

@@ -0,0 +1,5 @@
+import { defineConfig } from '@rstest/core';
+
+export default defineConfig({
+  projects: ['./project-b/rstest.config.ts', './project-a/rstest.config.ts'],
+});

e2e/browser-mode/fixtures/ports.ts

@@ -1,6 +1,13 @@
+/**
+ * Keep every fixture port unique.
+ *
+ * Browser-mode e2e tests can run concurrently in a single process. Reusing a port
+ * across fixtures can cause flaky "EADDRINUSE" failures.
+ */
 export const BROWSER_PORTS = {
   basic: 5180,
   'browser-react': 5202,
+  'locator-api': 5226,
   list: 5204,
   'no-tests': 5206,
   'entry-override': 5208,
@@ -22,3 +29,11 @@ export const BROWSER_PORTS = {
   'reporter-watch': 5222,
   'github-actions': 5224,
 } as const;
+
+const browserPortValues = Object.values(BROWSER_PORTS);
+
+if (new Set(browserPortValues).size !== browserPortValues.length) {
+  throw new Error(
+    `Duplicate browser fixture ports detected: ${JSON.stringify(BROWSER_PORTS)}`,
+  );
+}

e2e/browser-mode/locatorApi.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from '@rstest/core';
+import { runBrowserCli } from './utils';
+
+describe('browser mode - locator api', () => {
+  it('should run locator API tests correctly', async () => {
+    const { expectExecSuccess, cli } = await runBrowserCli('locator-api');
+
+    await expectExecSuccess();
+    expect(cli.stdout).toMatch(/Tests.*passed/);
+  });
+
+  it('should run locator API tests in headed mode without scheduler page', async () => {
+    const { expectExecSuccess, cli } = await runBrowserCli('locator-api', {
+      args: ['--browser.headless', 'false'],
+    });
+
+    await expectExecSuccess();
+    expect(cli.stdout).toMatch(/Tests.*passed/);
+    expect(cli.stdout).not.toContain('/scheduler.html');
+  });
+});

e2e/browser-mode/multiProjectConfig.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from '@rstest/core';
+import { runBrowserCli } from './utils';
+
+/**
+ * Regression test: in multi-project browser mode, each project must compile with
+ * its own config instead of inheriting config from the first browser project.
+ */
+describe('browser mode - multi project config isolation', () => {
+  it('should apply each browser project config independently', async () => {
+    const { expectExecSuccess, cli } = await runBrowserCli(
+      'multi-project-config',
+      {
+        args: ['project-a/tests/jsxRuntime.test.tsx'],
+      },
+    );
+
+    await expectExecSuccess();
+    expect(cli.stdout).toContain('jsxRuntime.test.tsx');
+    expect(cli.stdout).toMatch(/Tests.*passed/);
+  });
+});

e2e/browser-mode/viewport.test.ts

@@ -13,4 +13,14 @@ describe('browser mode - viewport', () => {
     await expectExecSuccess();
     expect(cli.stdout).toMatch(/Tests.*passed/);
   });
+
+  it('should apply viewport config in headed mode without scheduler page', async () => {
+    const { expectExecSuccess, cli } = await runBrowserCli('viewport', {
+      args: ['--browser.headless', 'false'],
+    });
+
+    await expectExecSuccess();
+    expect(cli.stdout).toMatch(/Tests.*passed/);
+    expect(cli.stdout).not.toContain('/scheduler.html');
+  });
 });

e2e/rstest.config.ts

@@ -13,7 +13,9 @@ export default defineConfig({
   setupFiles: ['../scripts/rstest.setup.ts'],
   // Increased timeout for CI to handle slower environments (e.g., Node.js 22 on Windows)
   // and reduce flaky timeouts caused by resource contention under high parallelism.
-  testTimeout: process.env.CI ? 60_000 : 10_000,
+  // Use the same timeout locally because browser-mode e2e tests can exceed 15s when
+  // running together with the full suite under high machine load.
+  testTimeout: process.env.CI ? 60_000 : 30_000,
   slowTestThreshold: 2_000,
   // Stabilize date/time based e2e fixtures across different runner timezones.
   // Some fixtures use `new Date('YYYY-MM-DD')` (UTC parsing) but assert on local

examples/browser-react/package.json

@@ -15,8 +15,6 @@
     "@rstest/browser": "workspace:*",
     "@rstest/browser-react": "workspace:*",
     "@rstest/core": "workspace:*",
-    "@testing-library/dom": "^10.4.1",
-    "@testing-library/user-event": "^14.6.1",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
     "playwright": "^1.58.2",