Data-Driven Testing in Playwright

Definition and Brief Explanation

Definition: Data-Driven Testing in Playwright is a framework design technique for keeping a Playwright test suite readable, reusable, and maintainable.

Explanation: Data-Driven Testing becomes important when tests grow beyond a few files. It should reduce duplication without hiding the behavior being tested or making failures harder to understand.

Why It Matters

• It makes the Playwright suite easier to understand and debug.
• It supports reliable automation instead of one-off scripts.
• It helps explain the topic in interviews with practical examples.
• It connects code behavior with user-facing results.

How It Works

1. Identify the role this topic plays in the test flow.
2. Use the Playwright API that directly matches the need.
3. Keep the example small enough to debug.
4. Add an assertion or verification that proves success.

Syntax and Examples

const users = [
  { email: '', error: 'Email is required' },
  { email: 'wrong', error: 'Enter a valid email' }
];

for (const user of users) {
  test(`email validation ${user.error}`, async ({ page }) => {
    await page.goto('/login');
    await page.getByLabel('Email').fill(user.email);
    await page.getByRole('button', { name: 'Login' }).click();
    await expect(page.getByText(user.error)).toBeVisible();
  });
}

Common Mistakes

• Using the API without understanding the test goal.
• Mixing too many unrelated checks in one example.
• Skipping verification after setup or action.
• Ignoring Playwright reports, traces, or failure messages.

Interview Notes

1. What is Data-Driven Testing?
2. Where does Data-Driven Testing fit in Playwright?
3. Can you show a realistic example?
4. What mistake would make this flaky?

Practice Task

Create a small Playwright example for Data-Driven Testing. Add one positive assertion, one note about what can go wrong, and one improvement that would make the test more maintainable.