Playwright skill

MCP Workflow (MANDATORY If Available)

⚠️ If you have Playwright MCP tools, ALWAYS use them BEFORE creating any test:

1. Navigate to target page
2. Take snapshot to see page structure and elements
3. Interact with forms/elements to verify exact user flow
4. Take screenshots to document expected states
5. Verify page transitions through complete flow (loading, success, error)
6. Document actual selectors from snapshots (use real refs and labels)
7. Only after exploring create test code with verified selectors

If MCP NOT available: Proceed with test creation based on docs and code analysis.

Why This Matters:

• ✅ Precise tests - exact steps needed, no assumptions
• ✅ Accurate selectors - real DOM structure, not imagined
• ✅ Real flow validation - verify journey actually works
• ✅ Avoid over-engineering - minimal tests for what exists
• ✅ Prevent flaky tests - real exploration = stable tests
• ❌ Never assume how UI "should" work

File Structure

tests/
├── base-page.ts              # Parent class for ALL pages
├── helpers.ts                # Shared utilities
└── {page-name}/
    ├── {page-name}-page.ts   # Page Object Model
    ├── {page-name}.spec.ts   # ALL tests here (NO separate files!)
    └── {page-name}.md        # Test documentation

File Naming:

• ✅ sign-up.spec.ts (all sign-up tests)
• ✅ sign-up-page.ts (page object)
• ✅ sign-up.md (documentation)
• ❌ sign-up-critical-path.spec.ts (WRONG - no separate files)
• ❌ sign-up-validation.spec.ts (WRONG)

Selector Priority (REQUIRED)

// 1. BEST - getByRole for interactive elements
this.submitButton = page.getByRole("button", { name: "Submit" });
this.navLink = page.getByRole("link", { name: "Dashboard" });

// 2. BEST - getByLabel for form controls
this.emailInput = page.getByLabel("Email");
this.passwordInput = page.getByLabel("Password");

// 3. SPARINGLY - getByText for static content only
this.errorMessage = page.getByText("Invalid credentials");
this.pageTitle = page.getByText("Welcome");

// 4. LAST RESORT - getByTestId when above fail
this.customWidget = page.getByTestId("date-picker");

// ❌ AVOID fragile selectors
this.button = page.locator(".btn-primary");  // NO
this.input = page.locator("#email");         // NO

Scope Detection (ASK IF AMBIGUOUS)

User Says	Action
"a test", "one test", "new test", "add test"	Create ONE test() in existing spec
"comprehensive tests", "all tests", "test suite", "generate tests"	Create full suite

Examples:

• "Create a test for user sign-up" → ONE test only
• "Generate E2E tests for login page" → Full suite
• "Add a test to verify form validation" → ONE test to existing spec

Page Object Pattern

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

// BasePage - ALL pages extend this
export class BasePage {
  constructor(protected page: Page) {}

  async goto(path: string): Promise<void> {
    await this.page.goto(path);
    await this.page.waitForLoadState("networkidle");
  }

  // Common methods go here (see Refactoring Guidelines)
  async waitForNotification(): Promise<void> {
    await this.page.waitForSelector('[role="status"]');
  }

  async verifyNotificationMessage(message: string): Promise<void> {
    const notification = this.page.locator('[role="status"]');
    await expect(notification).toContainText(message);
  }
}

// Page-specific implementation
export interface LoginData {
  email: string;
  password: string;
}

export class LoginPage extends BasePage {
  readonly emailInput: Locator;
  readonly passwordInput: Locator;
  readonly submitButton: Locator;

  constructor(page: Page) {
    super(page);
    this.emailInput = page.getByLabel("Email");
    this.passwordInput = page.getByLabel("Password");
    this.submitButton = page.getByRole("button", { name: "Sign in" });
  }

  async goto(): Promise<void> {
    await super.goto("/login");
  }

  async login(data: LoginData): Promise<void> {
    await this.emailInput.fill(data.email);
    await this.passwordInput.fill(data.password);
    await this.submitButton.click();
  }

  async verifyCriticalOutcome(): Promise<void> {
    await expect(this.page).toHaveURL("/dashboard");
  }
}

Page Object Reuse (CRITICAL)

Always check existing page objects before creating new ones!

// ✅ GOOD: Reuse existing page objects
import { SignInPage } from "../sign-in/sign-in-page";
import { HomePage } from "../home/home-page";

test("User can sign up and login", async ({ page }) => {
  const signUpPage = new SignUpPage(page);
  const signInPage = new SignInPage(page);  // REUSE
  const homePage = new HomePage(page);      // REUSE

  await signUpPage.signUp(userData);
  await homePage.verifyPageLoaded();  // REUSE method
  await homePage.signOut();           // REUSE method
  await signInPage.login(credentials); // REUSE method
});

// ❌ BAD: Recreating existing functionality
export class SignUpPage extends BasePage {
  async logout() { /* ... */ }  // ❌ HomePage already has this
  async login() { /* ... */ }   // ❌ SignInPage already has this
}

Guidelines:

• Check tests/ for existing page objects first
• Import and reuse existing pages
• Create page objects only when page doesn't exist
• If test requires multiple pages, ensure all page objects exist (create if needed)

Refactoring Guidelines

Move to BasePage when:

• ✅ Navigation helpers used by multiple pages (waitForPageLoad(), getCurrentUrl())
• ✅ Common UI interactions (notifications, modals, theme toggles)
• ✅ Verification patterns repeated across pages (isVisible(), waitForVisible())
• ✅ Error handling that applies to all pages
• ✅ Screenshot utilities for debugging

Move to helpers.ts when:

• ✅ Test data generation (generateUniqueEmail(), generateTestUser())
• ✅ Setup/teardown utilities (createTestUser(), cleanupTestData())
• ✅ Custom assertions (expectNotificationToContain())
• ✅ API helpers for test setup (seedDatabase(), resetState())
• ✅ Time utilities (waitForCondition(), retryAction())

Before (BAD):

// Repeated in multiple page objects
export class SignUpPage extends BasePage {
  async waitForNotification(): Promise<void> {
    await this.page.waitForSelector('[role="status"]');
  }
}
export class SignInPage extends BasePage {
  async waitForNotification(): Promise<void> {
    await this.page.waitForSelector('[role="status"]');  // DUPLICATED!
  }
}

After (GOOD):

// BasePage - shared across all pages
export class BasePage {
  async waitForNotification(): Promise<void> {
    await this.page.waitForSelector('[role="status"]');
  }
}

// helpers.ts - data generation
export function generateUniqueEmail(): string {
  return `test.${Date.now()}@example.com`;
}

export function generateTestUser() {
  return {
    name: "Test User",
    email: generateUniqueEmail(),
    password: "TestPassword123!",
  };
}

Test Pattern with Tags

import { test, expect } from "@playwright/test";
import { LoginPage } from "./login-page";

test.describe("Login", () => {
  test("User can login successfully",
    { tag: ["@critical", "@e2e", "@login", "@LOGIN-E2E-001"] },
    async ({ page }) => {
      const loginPage = new LoginPage(page);

      await loginPage.goto();
      await loginPage.login({ email: "user@test.com", password: "pass123" });

      await expect(page).toHaveURL("/dashboard");
    }
  );
});

Tag Categories:

• Priority: @critical, @high, @medium, @low
• Type: @e2e
• Feature: @signup, @signin, @dashboard
• Test ID: @SIGNUP-E2E-001, @LOGIN-E2E-002

Test Documentation Format ({page-name}.md)

### E2E Tests: {Feature Name}

**Suite ID:** `{SUITE-ID}`
**Feature:** {Feature description}

---

## Test Case: `{TEST-ID}` - {Test case title}

**Priority:** `{critical|high|medium|low}`

**Tags:**
- type → @e2e
- feature → @{feature-name}

**Description/Objective:** {Brief description}

**Preconditions:**
- {Prerequisites for test to run}
- {Required data or state}

### Flow Steps:
1. {Step 1}
2. {Step 2}
3. {Step 3}

### Expected Result:
- {Expected outcome 1}
- {Expected outcome 2}

### Key verification points:
- {Assertion 1}
- {Assertion 2}

### Notes:
- {Additional considerations}

Documentation Rules:

• ❌ NO general test running instructions
• ❌ NO file structure explanations
• ❌ NO code examples or tutorials
• ❌ NO troubleshooting sections
• ✅ Focus ONLY on specific test case
• ✅ Keep under 60 lines when possible

Commands

npx playwright test                    # Run all
npx playwright test --grep "login"     # Filter by name
npx playwright test --ui               # Interactive UI
npx playwright test --debug            # Debug mode
npx playwright test tests/login/       # Run specific folder

Keywords

playwright, e2e, testing, page object model, selectors, end-to-end, mcp