Stripe Playwright Testing Interview Questions & Answers

obj?.a?.b safely reads nested properties and returns undefined instead of throwing if something in the chain is missing.

Read the next page link or IDs from earlier responses, loop until done and assert counts and uniqueness; pass IDs between calls in the same test.

await expect(page).toHaveScreenshot('home.png') compares against a baseline image; tune maxDiffPixels and mask dynamic areas like dates.

string, number, boolean, null, undefined, symbol, bigint and object (including arrays and functions).

Run npm init playwright@latest, which sets up config, example tests and browsers; execute with npx playwright test.

await page.route('**/api/users', route => route.fulfill({ status: 200, json: [{ id: 1, name: 'Test' }] }) );

In a fixture or beforeEach, call the API (request.post) to create the user or order, use it in the UI test, then delete it in teardown. It is faster and more reliable than creating data through the UI.

TypeScript adds static types on top of JavaScript and compiles to it. Types catch errors early and give better autocomplete, which helps in larger test suites.

Click to open the control, then use getByRole('option') or a text locator for the target item, instead of relying on fragile index-based selectors.

beforeEach runs the same code before every test in scope; fixtures are lazy, composable and only set up what a test uses.

npm is the Node package manager. package.json lists the project's dependencies and scripts, such as the command that runs the tests.

setInputFiles on the input for uploads; for downloads wait on page.waitForEvent('download') and save or inspect the file.

await request.post('/api/users', { data: { name: 'Asha' } }) automatically sets JSON headers and serialises the payload.

POST the query and variables as JSON to the single endpoint and assert both data and errors fields in the response.

var is function-scoped and hoisted. let and const are block-scoped; const can't be reassigned (though an object it points to can change). Prefer const, then let.

Use --debug or the Inspector, page.pause(), UI mode, the trace viewer and headed runs with slowMo.

const [newPage] = await Promise.all([ context.waitForEvent('page'), page.getByText('Open').click(), ]); await newPage.waitForLoadState();

Set them in the context options (geolocation, permissions, timezoneId, locale) to simulate users from other regions.

A short function syntax that does not have its own this and arguments, taking them from the surrounding scope.

Use the official Playwright image which contains browsers and dependencies, mount the project and run npx playwright test for consistent CI environments.

Scripts that run once before or after the whole run, for seeding data, starting services or creating authentication state.

Assert the status with expect(res.status()).toBe(200), parse res.json() and check fields, using schema validation for the structure.

Set extraHTTPHeaders in the config or pass headers per request, for example Authorization: Bearer token fetched in a setup step.

Log in once in global setup, save storageState to a JSON file and set use.storageState in the config so every test starts logged in.

Use environment variables or .env files, a baseURL in config, API calls for setup and cleanup, and unique data per run.

Use dotenv files per environment, read them in playwright.config and set baseURL and credentials from variables, selecting with an ENV flag.

npx playwright test tests/login.spec.ts, add -g "test title" to match a name, or use test.only while debugging.

await expect.soft(locator).toHaveText('...') records the failure but lets the test continue, so you see every mismatch in one run.

Use timeout and expect.timeout in config, test.setTimeout() for one test and test.slow() for known slower tests.

Use the request fixture: const res = await request.get('/api/users'); expect(res.ok()).toBeTruthy(); const body = await res.json();

all waits for every promise and rejects on the first failure; allSettled waits for all and reports each outcome; race settles with the first one to finish.

Install the allure-playwright reporter, add it in the config reporters array and generate the report from the allure-results folder in CI.

Record timestamps around the request or use response timing, then assert the duration is under an agreed threshold.

Add retries with backoff for the API step, set a suitable timeout, and use mocks for non-critical dependencies.

Set retries in the config or CLI and failed tests re-run in a fresh context, with trace recorded on first retry to diagnose flakiness.

Destructuring pulls values from arrays or objects into variables; spread expands an array or object into another, useful for copying and merging config.

Use page.route to intercept the call and fulfil it with fixed JSON so tests do not depend on external systems.

locator.hover() and locator.dragTo(target) perform these actions, with auto-waiting for actionability.

Rely on auto-waiting plus a web-first assertion on the final state, disable animations in config for tests and avoid fixed timeouts.

test('login', async ({ page }) => { await page.goto('/login'); await page.getByLabel('Email').fill('a@b.com'); await page.getByLabel('Password').fill('secret'); await page.getByRole('button', { name: 'Login' }).click(); await expect(page.getByRole('heading', { name: 'Dashboard' })).toBeVisible(); });

A Locator is lazy, re-resolved on every action and auto-waits (recommended). An ElementHandle points to one DOM node and can go stale.

Use page.waitForResponse(res => res.url().includes('/api/orders') && res.ok()) together with the action that triggers it.

Define an interface for the payload, cast or validate the parsed JSON to it (for example with zod), and use that type in assertions to catch shape changes.

Use try-catch with await, or .catch() on promises, and make sure rejected promises are never left unhandled.

Playwright supports multiple browsers, tabs, languages and has auto-waiting and tracing; Selenium has the widest ecosystem; Cypress runs in-browser with a great UI but has more limits across tabs.

Fixtures set up and tear down test dependencies. Extend with test.extend({ loggedInPage: async ({ page }, use) => { ...; await use(page); } }).

Both describe object shapes. Interfaces can be extended and merged; type aliases can also describe unions and primitives. Use interfaces for page or test-data shapes, types for unions.

Cover happy path, validation errors, auth and permissions, boundary values, idempotency, schema, performance and data cleanup.

TypeScript + POM + custom fixtures, environment configs, API helpers for test data, tags like @smoke, sharding across CI machines, retries with traces, HTML/Allure reports, lint and review rules.

Placeholders for types that make reusable code type-safe, for example a helper function returning the same type of item that it receives.

Fetch tokens in a fixture with expiry tracking and refresh it when it is about to expire, keeping tests unaware of the details.

Functions that take other functions as arguments or return them, such as map, filter and reduce, or a helper that wraps retry logic around a test step.

waitForSelector is a lower-level wait; locator assertions are preferred as they retry and are more readable.

Synchronous code runs line by line and blocks; asynchronous code starts a task and continues, handling the result later with promises or await.

Add tags in the title (@smoke) or use the tag option, and run with --grep @smoke or --grep-invert.

An object describing how to find an element, re-evaluated on every action so it always targets the current DOM.

Auto-waiting, a built-in test runner, Chromium/Firefox/WebKit with one API, network interception, the trace viewer and parallel runs out of the box — usually faster and less flaky.

A function that remembers variables from its outer scope even after that scope has finished. They are used for private state and factory helpers.

page.screenshot() for captures and config options use: { screenshot: 'only-on-failure', video: 'retain-on-failure' } for automatic evidence.

Both describe the shape of data. Interfaces are extendable and suit object contracts; type aliases can also model unions and primitives.