Playwright Compat Demo

A small React tutorial that demonstrates the in-browser Playwright-compatible test runner. The spec file is shaped like real @playwright/test code so students can later copy the same ideas into a Node/Vite project.

1

Run a Playwright-Style Todo Test

Learning objective: After this step you will be able to recognize the basic shape of a Playwright end-to-end test for a React app: navigate to the app, find elements the way a user would, perform actions, and assert what changed.

This demo uses the tutorial system’s Playwright-compatible runner. It does not start a real browser process on the backend, but the test file is intentionally close to normal @playwright/test:

import { test, expect } from '@playwright/test';

test('adds a todo item', async ({ page }) => {
  await page.goto('/');
  await page.getByRole('textbox', { name: /todo item/i }).fill('Milk');
  await page.getByRole('button', { name: /add todo/i }).click();
  await expect(page.getByText('Milk')).toBeVisible();
});

The preview iframe acts like the browser page. The test talks to it through Playwright-style APIs such as page.getByRole, locator.fill, locator.click, and expect(locator).toBeVisible().

Task

  1. Open tests/todo.spec.js.
  2. Click Test in the Live Preview toolbar and confirm the Playwright-style spec passes.
  3. Read the selectors and compare them to the labels, button text, and list items in src/App.jsx.
  4. Optional: add the final assertion from the solution to check that the input is cleared after adding a todo.
  5. Click Test My Work to run instructor checks that inspect the app and the test file itself.

In a real local project, the same spec would live under tests/ and run with npx playwright test. Here, package.json and playwright.config.js are included as reference files so students can see the normal project shape.

Starter files
src/App.jsx
function App() {
  const [items, setItems] = React.useState([]);
  const [text, setText] = React.useState('');

  function addTodo() {
    const trimmed = text.trim();
    if (!trimmed) return;

    setItems([...items, trimmed]);
    setText('');
  }

  return (
    <main className="todo-shell">
      <section className="todo-panel">
        <p className="eyebrow">Playwright demo</p>
        <h1>Todo Lab</h1>

        <div className="todo-form">
          <label htmlFor="todo-input">Todo item</label>
          <div className="todo-row">
            <input
              id="todo-input"
              value={text}
              onChange={(event) => setText(event.target.value)}
              placeholder="Buy milk"
            />
            <button onClick={addTodo}>Add todo</button>
          </div>
        </div>

        <ul aria-label="Todo list" className="todo-list">
          {items.map((item, index) => (
            <li key={index}>{item}</li>
          ))}
        </ul>
      </section>
    </main>
  );
}
src/main.jsx
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<App />);
src/styles.css
body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f6f7fb;
  color: #1f2937;
}

.todo-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 32px;
}

.todo-panel {
  width: min(100%, 560px);
  background: white;
  border: 1px solid #d9dee8;
  border-radius: 8px;
  padding: 28px;
  box-shadow: 0 18px 40px rgba(31, 41, 55, 0.08);
}

.eyebrow {
  margin: 0 0 8px;
  color: #4b5563;
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

h1 {
  margin: 0 0 24px;
  font-size: 2rem;
}

label {
  display: block;
  margin-bottom: 8px;
  font-weight: 700;
}

.todo-row {
  display: flex;
  gap: 10px;
}

input {
  flex: 1;
  min-width: 0;
  border: 1px solid #b8c0cc;
  border-radius: 6px;
  padding: 10px 12px;
  font: inherit;
}

button {
  border: 0;
  border-radius: 6px;
  padding: 10px 14px;
  background: #2563eb;
  color: white;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

.todo-list {
  margin: 24px 0 0;
  padding-left: 24px;
}

.todo-list:empty {
  display: none;
}

.todo-list li {
  margin: 8px 0;
}
tests/todo.spec.js
import { test, expect } from '@playwright/test';

test('adds a todo item', async ({ page }) => {
  await page.goto('/');

  await page.getByRole('textbox', { name: /todo item/i }).fill('Milk');
  await page.getByRole('button', { name: /add todo/i }).click();

  await expect(page.getByRole('listitem')).toHaveCount(1);
  await expect(page.getByText('Milk')).toBeVisible();
});

test('clears the input after adding', async ({ page }) => {
  await page.goto('/');

  const input = page.getByRole('textbox', { name: /todo item/i });

  await input.fill('Bread');
  await page.getByRole('button', { name: /add todo/i }).click();

  await expect(input).toHaveValue('');
  await expect(page.getByRole('listitem')).toHaveText('Bread');
});
playwright.config.js
const { defineConfig } = require('@playwright/test');

module.exports = defineConfig({
  testDir: './tests',
  use: {
    baseURL: 'http://localhost:5173',
  },
});
package.json
{
  "scripts": {
    "dev": "vite",
    "test:e2e": "playwright test"
  },
  "dependencies": {
    "react": "^18.2.0",
    "react-dom": "^18.2.0"
  },
  "devDependencies": {
    "@playwright/test": "^1.58.2",
    "@vitejs/plugin-react": "^5.0.0",
    "vite": "^7.0.0"
  }
}
2

Assert That a Student Test Fails

Learning objective: After this step you will be able to use an instructor check that expects one student-authored Playwright test to fail.

This step intentionally gives you a buggy Todo app: it adds items, but it does not clear the input afterward.

A good end-to-end test for the missing behavior should fail against this buggy app. That is useful in TDD and regression testing because a test that already passes against broken code may not be testing the right thing.

Task

  1. Open buggy/tests/todo.spec.js.
  2. Click Test in the Live Preview toolbar.
  3. Confirm that adds a todo item passes and clears the input after adding fails.
  4. Click Test My Work. The instructor check passes only if the named student test fails.
Starter files
buggy/src/App.jsx
function App() {
  const [items, setItems] = React.useState([]);
  const [text, setText] = React.useState('');

  function addTodo() {
    const trimmed = text.trim();
    if (!trimmed) return;

    setItems([...items, trimmed]);
    // Bug for the lesson: the app should clear the input here, but does not.
  }

  return (
    <main className="todo-shell">
      <section className="todo-panel">
        <p className="eyebrow">Buggy app</p>
        <h1>Todo Lab</h1>

        <label htmlFor="todo-input">Todo item</label>
        <div className="todo-row">
          <input
            id="todo-input"
            value={text}
            onChange={(event) => setText(event.target.value)}
            placeholder="Buy milk"
          />
          <button onClick={addTodo}>Add todo</button>
        </div>

        <ul aria-label="Todo list" className="todo-list">
          {items.map((item, index) => (
            <li key={index}>{item}</li>
          ))}
        </ul>
      </section>
    </main>
  );
}
buggy/src/main.jsx
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<App />);
buggy/src/styles.css
body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f6f7fb;
  color: #1f2937;
}

.todo-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 32px;
}

.todo-panel {
  width: min(100%, 520px);
  background: white;
  border: 1px solid #d9dee8;
  border-radius: 8px;
  padding: 28px;
}

.eyebrow {
  margin: 0 0 8px;
  color: #4b5563;
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
}

.todo-row {
  display: flex;
  gap: 10px;
  margin-top: 8px;
}

input {
  flex: 1;
  min-width: 0;
  border: 1px solid #b8c0cc;
  border-radius: 6px;
  padding: 10px 12px;
  font: inherit;
}

button {
  border: 0;
  border-radius: 6px;
  padding: 10px 14px;
  background: #2563eb;
  color: white;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}
buggy/tests/todo.spec.js
import { test, expect } from '@playwright/test';

test('adds a todo item', async ({ page }) => {
  await page.goto('/');

  await page.getByRole('textbox', { name: /todo item/i }).fill('Milk');
  await page.getByRole('button', { name: /add todo/i }).click();

  await expect(page.getByRole('listitem')).toHaveText('Milk');
});

test('clears the input after adding', async ({ page }) => {
  await page.goto('/');

  const input = page.getByRole('textbox', { name: /todo item/i });

  await input.fill('Milk');
  await page.getByRole('button', { name: /add todo/i }).click();

  await expect(input).toHaveValue('');
});