aehrc/playwright-testing

Playwright Testing

End-to-end testing framework with auto-waiting, web-first assertions, and multi-browser support.

Quick Start

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

test("user can log in", async ({ page }) => {
    await page.goto("/login");
    await page.getByLabel("Email").fill("[email protected]");
    await page.getByLabel("Password").fill("secret");
    await page.getByRole("button", { name: "Sign in" }).click();
    await expect(page.getByText("Welcome")).toBeVisible();
});

Core Concepts

Locators (Priority Order)

1. page.getByRole('button', { name: 'Submit' }) — ARIA roles (most resilient)
2. page.getByLabel('Email') — Form labels
3. page.getByText('Welcome') — Visible text
4. page.getByTestId('user-menu') — Test IDs (explicit contracts)
5. page.getByPlaceholder('Search') — Placeholder text

Avoid CSS selectors and XPath—they break with DOM changes.

Chaining and filtering:

// Chain to narrow scope
page.locator(".modal").getByRole("button", { name: "Save" });

// Filter by text or child elements
page.getByRole("listitem").filter({ hasText: "Product" });
page.getByRole("listitem").filter({ has: page.getByRole("button") });

See references/locators.md for complete locator API.

Assertions

Auto-retrying (use these for web elements):

await expect(locator).toBeVisible();
await expect(locator).toHaveText("Hello");
await expect(locator).toHaveValue("input text");
await expect(locator).toBeChecked();
await expect(page).toHaveURL(/dashboard/);

Non-retrying (for static values):

expect(value).toBe(5);
expect(array).toContain("item");
expect(obj).toEqual({ key: "value" });

See references/assertions.md for all assertion types.

Actions

await locator.click();
await locator.fill("text"); // Clear and type
await locator.pressSequentially("t"); // Character by character
await locator.selectOption("value");
await locator.check(); // Checkbox
await locator.setInputFiles("file.pdf");
await page.keyboard.press("Enter");

All actions auto-wait for elements to be visible, stable, and enabled.

See references/actions.md for complete action reference.

Test Structure

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

test.describe("Feature", () => {
    test.beforeEach(async ({ page }) => {
        await page.goto("/");
    });

    test("scenario one", async ({ page }) => {
        // Arrange - Act - Assert
    });

    test("scenario two", async ({ page }) => {
        // ...
    });
});

Hooks

• test.beforeEach() / test.afterEach() — Run before/after each test
• test.beforeAll() / test.afterAll() — Run once per worker

Configuration

Minimal playwright.config.ts:

import { defineConfig, devices } from "@playwright/test";

export default defineConfig({
    testDir: "./tests",
    fullyParallel: true,
    retries: process.env.CI ? 2 : 0,
    workers: process.env.CI ? 2 : undefined,
    reporter: "html",
    use: {
        baseURL: "http://localhost:3000",
        trace: "on-first-retry",
    },
    projects: [
        { name: "chromium", use: { ...devices["Desktop Chrome"] } },
        { name: "firefox", use: { ...devices["Desktop Firefox"] } },
        { name: "webkit", use: { ...devices["Desktop Safari"] } },
    ],
    webServer: {
        command: "npm run dev",
        url: "http://localhost:3000",
        reuseExistingServer: !process.env.CI,
    },
});

See references/configuration.md for all options.

CLI Commands

npx playwright test                    # Run all tests
npx playwright test --ui               # Interactive UI mode
npx playwright test --headed           # Show browser
npx playwright test --debug            # Step-through debugger
npx playwright test -g "login"         # Filter by title
npx playwright test --project=chromium # Specific browser
npx playwright test --last-failed      # Retry failures only
npx playwright codegen                 # Generate tests
npx playwright show-report             # View HTML report

Advanced Features

Network Mocking

await page.route("**/api/users", (route) =>
    route.fulfill({ json: [{ id: 1, name: "Mock User" }] }),
);

await page.route("**/api/error", (route) => route.fulfill({ status: 500 }));

Authentication State

// Save auth state after login
await page.context().storageState({ path: "auth.json" });

// Reuse in config
use: {
    storageState: "auth.json";
}

Fixtures

const test = base.extend<{ userPage: Page }>({
    userPage: async ({ browser }, use) => {
        const context = await browser.newContext();
        const page = await context.newPage();
        await page.goto("/login");
        // ... login
        await use(page);
        await context.close();
    },
});

See references/advanced.md for network mocking, auth patterns, fixtures, and Page Object Model.

Best Practices

1. Use role-based locators — getByRole() is most resilient to changes
2. Prefer auto-retrying assertions — await expect(locator).toBeVisible() not locator.isVisible()
3. Keep tests isolated — Each test gets fresh browser context
4. Avoid hardcoded waits — Playwright auto-waits; use explicit waits only for custom conditions
5. Test user behaviour — Focus on what users see, not implementation details
6. Use soft assertions sparingly — expect.soft() continues after failure for comprehensive reports