# Authentication Testing

## Table of Contents

1. [Quick Reference](#quick-reference)
2. [Patterns](#patterns)
3. [Decision Guide](#decision-guide)
4. [Anti-Patterns](#anti-patterns)
5. [Troubleshooting](#troubleshooting)
6. [Related](#related)

> **When to use**: Apps with login, session management, or protected routes. Authentication is the most common source of slow test suites.

## Quick Reference

```typescript
// Storage state reuse — the #1 pattern for fast auth
await page.goto("/login");
await page.getByLabel("Username").fill("testuser@example.com");
await page.getByLabel("Password").fill("secretPass123");
await page.getByRole("button", { name: "Log in" }).click();
await page.context().storageState({ path: ".auth/session.json" });

// Reuse in config — every test starts authenticated
{
  use: {
    storageState: ".auth/session.json"
  }
}

// API login — skip the UI entirely
const context = await browser.newContext();
const response = await context.request.post("/api/auth/login", {
  data: { email: "testuser@example.com", password: "secretPass123" },
});
await context.storageState({ path: ".auth/session.json" });
```

## Patterns

### Storage State Reuse

**Use when**: You need authenticated tests and want to avoid logging in before every test.
**Avoid when**: Tests require completely fresh sessions, or you are testing the login flow itself.

`storageState` serializes cookies and localStorage to a JSON file. Load it in any browser context to start authenticated instantly.

```typescript
// scripts/generate-auth.ts — run once to generate the state file
import { chromium } from "@playwright/test";

async function generateAuthState() {
  const browser = await chromium.launch();
  const context = await browser.newContext();
  const page = await context.newPage();

  await page.goto("http://localhost:4000/login");
  await page.getByLabel("Username").fill("testuser@example.com");
  await page.getByLabel("Password").fill("secretPass123");
  await page.getByRole("button", { name: "Log in" }).click();
  await page.waitForURL("/home");

  await context.storageState({ path: ".auth/session.json" });
  await browser.close();
}

generateAuthState();
```

```typescript
// playwright.config.ts — load saved state for all tests
import { defineConfig } from "@playwright/test";

export default defineConfig({
  use: {
    baseURL: "http://localhost:4000",
    storageState: ".auth/session.json",
  },
});
```

```typescript
// tests/home.spec.ts — test starts already logged in
import { test, expect } from "@playwright/test";

test("authenticated user sees home page", async ({ page }) => {
  await page.goto("/home");
  await expect(page.getByRole("heading", { name: "Home" })).toBeVisible();
});
```

### Global Setup Authentication

**Use when**: You want to authenticate once before the entire test suite runs.
**Avoid when**: Different tests need different users, or your tokens expire faster than your suite runs.

```typescript
// global-setup.ts
import { chromium, type FullConfig } from "@playwright/test";

async function globalSetup(config: FullConfig) {
  const { baseURL } = config.projects[0].use;
  const browser = await chromium.launch();
  const context = await browser.newContext();
  const page = await context.newPage();

  await page.goto(`${baseURL}/login`);
  await page.getByLabel("Username").fill(process.env.TEST_USER_EMAIL!);
  await page.getByLabel("Password").fill(process.env.TEST_USER_PASSWORD!);
  await page.getByRole("button", { name: "Log in" }).click();
  await page.waitForURL("**/home");

  await context.storageState({ path: ".auth/session.json" });
  await browser.close();
}

export default globalSetup;
```

```typescript
// playwright.config.ts
import { defineConfig } from "@playwright/test";

export default defineConfig({
  globalSetup: require.resolve("./global-setup"),
  use: {
    baseURL: "http://localhost:4000",
    storageState: ".auth/session.json",
  },
});
```

Add `.auth/` to `.gitignore`. Auth state files contain session tokens and should never be committed.

### Per-Worker Authentication

**Use when**: Each parallel worker needs its own authenticated session to avoid race conditions for tests that modify server-side state.
**Avoid when**: Tests are read-only and a modifying shared session is safe, you can use a single shared account.

> **Sharded runs**: `parallelIndex` resets per shard, so different shards can have workers with the same index. To avoid collisions, include the shard identifier in the username (e.g., `worker-${SHARD_INDEX}-${parallelIndex}@example.com`) by passing a `SHARD_INDEX` environment variable from your CI matrix.

```typescript
// fixtures/auth.ts
import { test as base, type BrowserContext } from "@playwright/test";

type AuthFixtures = {
  authenticatedContext: BrowserContext;
};

export const test = base.extend<{}, AuthFixtures>({
  authenticatedContext: [
    async ({ browser }, use) => {
      const context = await browser.newContext();
      const page = await context.newPage();

      await page.goto("/login");
      await page
        .getByLabel("Username")
        .fill(`worker-${test.info().parallelIndex}@example.com`);
      await page.getByLabel("Password").fill("secretPass123");
      await page.getByRole("button", { name: "Log in" }).click();
      await page.waitForURL("/home");
      await page.close();

      await use(context);
      await context.close();
    },
    { scope: "worker" },
  ],
});

export { expect } from "@playwright/test";
```

```typescript
// tests/settings.spec.ts
import { test, expect } from "../fixtures/auth";

test("update display name", async ({ authenticatedContext }) => {
  const page = await authenticatedContext.newPage();
  await page.goto("/settings/profile");
  await page.getByLabel("Display name").fill("Updated Name");
  await page.getByRole("button", { name: "Save" }).click();
  await expect(page.getByText("Profile saved")).toBeVisible();
});
```

### Multiple Roles

**Use when**: Your app has role-based access control and you need to test different permission levels.
**Avoid when**: Your app has a single user role.

```typescript
// global-setup.ts — authenticate all roles
import { chromium, type FullConfig } from "@playwright/test";

const accounts = [
  {
    role: "admin",
    email: "admin@example.com",
    password: process.env.ADMIN_PASSWORD!,
  },
  {
    role: "member",
    email: "member@example.com",
    password: process.env.MEMBER_PASSWORD!,
  },
  {
    role: "guest",
    email: "guest@example.com",
    password: process.env.GUEST_PASSWORD!,
  },
];

async function globalSetup(config: FullConfig) {
  const { baseURL } = config.projects[0].use;

  for (const { role, email, password } of accounts) {
    const browser = await chromium.launch();
    const context = await browser.newContext();
    const page = await context.newPage();

    await page.goto(`${baseURL}/login`);
    await page.getByLabel("Username").fill(email);
    await page.getByLabel("Password").fill(password);
    await page.getByRole("button", { name: "Log in" }).click();
    await page.waitForURL("**/home");

    await context.storageState({ path: `.auth/${role}.json` });
    await browser.close();
  }
}

export default globalSetup;
```

```typescript
// playwright.config.ts — one project per role
import { defineConfig } from "@playwright/test";

export default defineConfig({
  globalSetup: require.resolve("./global-setup"),
  projects: [
    {
      name: "admin",
      use: { storageState: ".auth/admin.json" },
      testMatch: "**/*.admin.spec.ts",
    },
    {
      name: "member",
      use: { storageState: ".auth/member.json" },
      testMatch: "**/*.member.spec.ts",
    },
    {
      name: "guest",
      use: { storageState: ".auth/guest.json" },
      testMatch: "**/*.guest.spec.ts",
    },
    {
      name: "anonymous",
      use: { storageState: { cookies: [], origins: [] } },
      testMatch: "**/*.anon.spec.ts",
    },
  ],
});
```

```typescript
// tests/admin-panel.admin.spec.ts
import { test, expect } from "@playwright/test";

test("admin can access user management", async ({ page }) => {
  await page.goto("/admin/users");
  await expect(
    page.getByRole("heading", { name: "User Management" })
  ).toBeVisible();
  await expect(page.getByRole("button", { name: "Remove user" })).toBeEnabled();
});
```

```typescript
// tests/admin-panel.guest.spec.ts
import { test, expect } from "@playwright/test";

test("guest cannot access admin panel", async ({ page }) => {
  await page.goto("/admin/users");
  await expect(page.getByText("Access denied")).toBeVisible();
});
```

**Alternative**: Use a fixture that accepts a role parameter when you need role switching within a single spec file.

```typescript
// fixtures/auth.ts — role-based fixture
import { test as base, type Page } from "@playwright/test";
import fs from "fs";

type RoleFixtures = {
  loginAs: (role: "admin" | "member" | "guest") => Promise<Page>;
};

export const test = base.extend<RoleFixtures>({
  loginAs: async ({ browser }, use) => {
    const pages: Page[] = [];

    await use(async (role) => {
      const statePath = `.auth/${role}.json`;
      if (!fs.existsSync(statePath)) {
        throw new Error(
          `Auth state for role "${role}" not found at ${statePath}`
        );
      }
      const context = await browser.newContext({ storageState: statePath });
      const page = await context.newPage();
      pages.push(page);
      return page;
    });

    for (const page of pages) {
      await page.context().close();
    }
  },
});

export { expect } from "@playwright/test";
```

```typescript
// tests/role-comparison.spec.ts
import { test, expect } from "../fixtures/auth";

test("admin sees remove button, guest does not", async ({ loginAs }) => {
  const adminPage = await loginAs("admin");
  await adminPage.goto("/admin/users");
  await expect(
    adminPage.getByRole("button", { name: "Remove user" })
  ).toBeVisible();

  const guestPage = await loginAs("guest");
  await guestPage.goto("/admin/users");
  await expect(guestPage.getByText("Access denied")).toBeVisible();
});
```

### OAuth/SSO Mocking

**Use when**: Your app authenticates via a third-party OAuth provider and you cannot hit the real provider in tests.
**Avoid when**: You have a dedicated test tenant on the OAuth provider.

A typical OAuth flow works like this:

1. User clicks "Sign in with Provider" → browser navigates to `https://accounts.provider.com/authorize?...`
2. User authenticates on the provider's page → provider redirects back to your app's **callback route** (e.g. `http://localhost:4000/auth/callback?code=ABC&state=XYZ`)
3. Your backend exchanges the `code` for an access token, creates a session, and redirects the user to a logged-in page

In tests you can short-circuit step 2 with `page.route()`: intercept the outbound request to the provider and respond with a `302` redirect straight to your callback route, supplying a mock `code` and `state`. Your backend still executes its normal callback handler — the only part that's mocked is the provider's authorization page.

For cases where you want to skip the browser redirect entirely, a second approach calls a **test-only API endpoint** that creates the session server-side and returns the session cookie directly.

```typescript
// tests/oauth-login.spec.ts — mock the callback route
import { test, expect } from "@playwright/test";

test("login via mocked OAuth flow", async ({ page }) => {
  await page.route("https://accounts.provider.com/**", async (route) => {
    const callbackUrl = new URL("http://localhost:4000/auth/callback");
    callbackUrl.searchParams.set("code", "mock-auth-code-xyz");
    callbackUrl.searchParams.set("state", "expected-state-value");
    await route.fulfill({
      status: 302,
      headers: { location: callbackUrl.toString() },
    });
  });

  await page.goto("/login");
  await page.getByRole("button", { name: "Sign in with Provider" }).click();

  await page.waitForURL("/home");
  await expect(page.getByRole("heading", { name: "Home" })).toBeVisible();
});
```

```typescript
// tests/oauth-login.spec.ts — API-based session injection
import { test, expect } from "@playwright/test";

test("bypass OAuth entirely via API session injection", async ({
  page,
}) => {
  // Call a test-only endpoint that creates a session without OAuth
  const response = await page.request.post("/api/test/create-session", {
    data: {
      email: "oauth-user@example.com",
      provider: "provider",
      role: "member",
    },
  });
  expect(response.ok()).toBeTruthy();

  await page.context().storageState({ path: ".auth/oauth-user.json" });
  await page.goto("/home");
  await expect(page.getByRole("heading", { name: "Home" })).toBeVisible();
});
```

**Backend requirement**: Your backend must expose a test-only session creation endpoint (guarded by `NODE_ENV=test`) or accept a known test OAuth code.

### MFA Handling

**Use when**: Your app requires two-factor authentication (TOTP, SMS, email codes).
**Avoid when**: MFA is optional and you can disable it for test accounts.

**Strategy 1**: Generate real TOTP codes from a shared secret.

```typescript
// helpers/totp.ts
import * as OTPAuth from "otpauth";

export function generateTOTP(secret: string): string {
  const totp = new OTPAuth.TOTP({
    secret: OTPAuth.Secret.fromBase32(secret),
    digits: 6,
    period: 30,
    algorithm: "SHA1",
  });
  return totp.generate();
}
```

```typescript
// tests/mfa-login.spec.ts
import { test, expect } from "@playwright/test";
import { generateTOTP } from "../helpers/totp";

test("login with TOTP two-factor auth", async ({ page }) => {
  await page.goto("/login");
  await page.getByLabel("Username").fill("mfa-user@example.com");
  await page.getByLabel("Password").fill("secretPass123");
  await page.getByRole("button", { name: "Log in" }).click();

  await expect(page.getByText("Enter your authentication code")).toBeVisible();

  const code = generateTOTP(process.env.MFA_TOTP_SECRET!);
  await page.getByLabel("Authentication code").fill(code);
  await page.getByRole("button", { name: "Verify" }).click();

  await page.waitForURL("/home");
  await expect(page.getByRole("heading", { name: "Home" })).toBeVisible();
});
```

**Strategy 2**: Mock MFA at the backend level. Have your backend accept a known bypass code (e.g., `000000`) when `NODE_ENV=test`.

**Strategy 3**: Disable MFA for test accounts at the infrastructure level.

### Session Refresh

**Use when**: Your tokens expire during long test runs.
**Avoid when**: Your test suite runs quickly and tokens outlast the entire run.

```typescript
// fixtures/auth-with-refresh.ts
import { test as base, type BrowserContext } from "@playwright/test";
import fs from "fs";

type AuthFixtures = {
  authenticatedPage: import("@playwright/test").Page;
};

export const test = base.extend<AuthFixtures>({
  authenticatedPage: async ({ browser }, use) => {
    const statePath = ".auth/session.json";

    let context: BrowserContext;
    if (fs.existsSync(statePath)) {
      context = await browser.newContext({ storageState: statePath });
      const page = await context.newPage();

      const response = await page.request.get("/api/auth/me");
      if (response.ok()) {
        await use(page);
        await context.close();
        return;
      }
      await context.close();
    }

    context = await browser.newContext();
    const page = await context.newPage();
    await page.goto("/login");
    await page.getByLabel("Username").fill(process.env.TEST_USER_EMAIL!);
    await page.getByLabel("Password").fill(process.env.TEST_USER_PASSWORD!);
    await page.getByRole("button", { name: "Log in" }).click();
    await page.waitForURL("/home");

    await context.storageState({ path: statePath });

    await use(page);
    await context.close();
  },
});

export { expect } from "@playwright/test";
```

### Login Page Object

**Use when**: Multiple test files need to log in and you want consistent, maintainable login logic.
**Avoid when**: You use `storageState` everywhere and never navigate through the login UI in tests.

```typescript
// page-objects/LoginPage.ts
import { type Page, type Locator, expect } from "@playwright/test";

export class LoginPage {
  readonly page: Page;
  readonly usernameInput: Locator;
  readonly passwordInput: Locator;
  readonly loginButton: Locator;
  readonly errorMessage: Locator;
  readonly forgotPasswordLink: Locator;

  constructor(page: Page) {
    this.page = page;
    this.usernameInput = page.getByLabel("Username");
    this.passwordInput = page.getByLabel("Password");
    this.loginButton = page.getByRole("button", { name: "Log in" });
    this.errorMessage = page.getByRole("alert");
    this.forgotPasswordLink = page.getByRole("link", {
      name: "Forgot password",
    });
  }

  async goto() {
    await this.page.goto("/login");
    await expect(this.loginButton).toBeVisible();
  }

  async login(username: string, password: string) {
    await this.usernameInput.fill(username);
    await this.passwordInput.fill(password);
    await this.loginButton.click();
  }

  async loginAndWaitForHome(username: string, password: string) {
    await this.login(username, password);
    await this.page.waitForURL("/home");
  }

  async expectError(message: string | RegExp) {
    await expect(this.errorMessage).toContainText(message);
  }

  async expectFieldError(field: "username" | "password", message: string) {
    const input =
      field === "username" ? this.usernameInput : this.passwordInput;
    await expect(input).toHaveAttribute("aria-invalid", "true");
    const errorId = await input.getAttribute("aria-describedby");
    if (errorId) {
      await expect(this.page.locator(`#${errorId}`)).toContainText(message);
    }
  }
}
```

```typescript
// tests/login.spec.ts
import { test, expect } from "@playwright/test";
import { LoginPage } from "../page-objects/LoginPage";

test.use({ storageState: { cookies: [], origins: [] } });

test.describe("login page", () => {
  let loginPage: LoginPage;

  test.beforeEach(async ({ page }) => {
    loginPage = new LoginPage(page);
    await loginPage.goto();
  });

  test("successful login redirects to home", async ({ page }) => {
    await loginPage.loginAndWaitForHome(
      "testuser@example.com",
      "secretPass123"
    );
    await expect(page.getByRole("heading", { name: "Home" })).toBeVisible();
  });

  test("wrong password shows error", async () => {
    await loginPage.login("testuser@example.com", "wrong-password");
    await loginPage.expectError("Invalid username or password");
  });

  test("empty fields show validation errors", async () => {
    await loginPage.loginButton.click();
    await loginPage.expectFieldError("username", "Username is required");
  });

  test("forgot password link navigates correctly", async ({ page }) => {
    await loginPage.forgotPasswordLink.click();
    await page.waitForURL("/forgot-password");
    await expect(
      page.getByRole("heading", { name: "Reset password" })
    ).toBeVisible();
  });
});
```

### API-Based Login

**Use when**: You want the fastest possible authentication without any browser interaction.
**Avoid when**: You are specifically testing the login UI.

API login is typically 5-10x faster than UI login.

```typescript
// global-setup.ts — API-based login (fastest)
import { request, type FullConfig } from "@playwright/test";

async function globalSetup(config: FullConfig) {
  const { baseURL } = config.projects[0].use;

  const requestContext = await request.newContext({ baseURL });

  const response = await requestContext.post("/api/auth/login", {
    data: {
      email: process.env.TEST_USER_EMAIL!,
      password: process.env.TEST_USER_PASSWORD!,
    },
  });

  if (!response.ok()) {
    throw new Error(
      `API login failed: ${response.status()} ${await response.text()}`
    );
  }

  await requestContext.storageState({ path: ".auth/session.json" });
  await requestContext.dispose();
}

export default globalSetup;
```

```typescript
// fixtures/api-auth.ts — fixture version for per-test authentication
import { test as base } from "@playwright/test";

export const test = base.extend({
  authenticatedPage: async ({ browser, playwright }, use) => {
    const apiContext = await playwright.request.newContext({
      baseURL: "http://localhost:4000",
    });

    await apiContext.post("/api/auth/login", {
      data: {
        email: "testuser@example.com",
        password: "secretPass123",
      },
    });

    const state = await apiContext.storageState();
    const context = await browser.newContext({ storageState: state });
    const page = await context.newPage();

    await use(page);

    await context.close();
    await apiContext.dispose();
  },
});

export { expect } from "@playwright/test";
```

### Unauthenticated Tests

**Use when**: Testing the login page, signup flow, password reset, public pages, or redirect behavior for unauthenticated users.
**Avoid when**: The test requires a logged-in user.

When your config sets a default `storageState`, you must explicitly clear it for unauthenticated tests.

```typescript
// tests/public-pages.spec.ts
import { test, expect } from "@playwright/test";

test.use({ storageState: { cookies: [], origins: [] } });

test.describe("unauthenticated access", () => {
  test("homepage is accessible without login", async ({ page }) => {
    await page.goto("/");
    await expect(page.getByRole("heading", { name: "Welcome" })).toBeVisible();
    await expect(page.getByRole("link", { name: "Log in" })).toBeVisible();
  });

  test("protected route redirects to login", async ({ page }) => {
    await page.goto("/home");
    await page.waitForURL("**/login**");
    expect(page.url()).toContain("redirect=%2Fhome");
  });

  test("expired session shows re-login prompt", async ({ page, context }) => {
    await page.goto("/home");
    await context.clearCookies();

    await page.goto("/settings");
    await page.waitForURL("**/login**");
    await expect(page.getByText("Your session has expired")).toBeVisible();
  });

  test("signup flow creates account", async ({ page }) => {
    await page.goto("/signup");
    await page.getByLabel("Name").fill("New User");
    await page.getByLabel("Email").fill(`test-${Date.now()}@example.com`);
    await page.getByLabel("Password", { exact: true }).fill("secretPass123");
    await page.getByLabel("Confirm password").fill("secretPass123");
    await page.getByRole("button", { name: "Create account" }).click();

    await page.waitForURL("/onboarding");
    await expect(page.getByText("Welcome, New User")).toBeVisible();
  });
});
```

## Decision Guide

| Scenario                         | Approach                       | Speed    | Isolation      | When to Choose                                                 |
| -------------------------------- | ------------------------------ | -------- | -------------- | -------------------------------------------------------------- |
| Most tests need auth             | Global setup + `storageState`  | Fastest  | Shared session | Default for nearly every project                               |
| Tests modify user state          | Per-worker fixture             | Fast     | Per worker     | Tests update profile, change settings, or mutate data          |
| Multiple user roles              | Per-project `storageState`     | Fastest  | Per role       | App has admin/member/guest roles                               |
| Testing the login page           | No `storageState`              | N/A      | Full           | Use `test.use({ storageState: { cookies: [], origins: [] } })` |
| OAuth/SSO provider               | Mock the callback              | Fast     | Per test       | Never hit real OAuth providers in CI                           |
| MFA is required                  | TOTP generation or bypass      | Moderate | Per test       | Generate real TOTP codes or use a test-mode bypass             |
| Token expires mid-suite          | Session refresh fixture        | Fast     | Per check      | Fixture validates the session before use                       |
| Single test needs different user | `loginAs(role)` fixture        | Moderate | Per call       | Rare: prefer per-project roles                                 |
| API-first app (no login UI)      | API login via `request.post()` | Fastest  | Per test       | No browser needed for auth                                     |

### UI Login vs API Login vs Storage State

```text
Need to test the login page itself?
├── Yes → UI login with LoginPage POM, no storageState
└── No → Do you have a login API endpoint?
    ├── Yes → API login in global setup, save storageState (fastest)
    └── No → UI login in global setup, save storageState
              └── Tokens expire quickly?
                  ├── Yes → Add session refresh fixture
                  └── No → Standard storageState reuse is fine
```

## Anti-Patterns

| Don't Do This                                                             | Problem                                     | Do This Instead                                                           |
| ------------------------------------------------------------------------- | ------------------------------------------- | ------------------------------------------------------------------------- |
| Log in via UI before every test                                           | Adds 2-5 seconds per test                   | Use `storageState` to skip login entirely                                 |
| Share a single auth state file across parallel workers that mutate state  | Race conditions                             | Use per-worker fixtures with `{ scope: 'worker' }`                        |
| Hardcode credentials in test files                                        | Security risk                               | Use environment variables and `.env` files                                |
| Ignore token expiration                                                   | Tests fail intermittently with 401 errors   | Add a session validity check in your auth fixture                         |
| Hit real OAuth providers in CI                                            | Flaky: rate limits, CAPTCHA, network issues | Mock the OAuth callback or use API session injection                      |
| Use `page.waitForTimeout(2000)` after login                               | Arbitrary delay                             | `await page.waitForURL('/home')` or `await expect(heading).toBeVisible()` |
| Store `.auth/*.json` files in git                                         | Tokens in version control                   | Add `.auth/` to `.gitignore`                                              |
| Create one "god" test account with all permissions                        | Cannot test role-based access control       | Create separate accounts per role                                         |
| Use `browser.newContext()` without `storageState` for authenticated tests | Every context starts unauthenticated        | Pass `storageState` when creating the context                             |
| Test MFA by disabling it everywhere                                       | You never test the MFA flow                 | Use TOTP generation for at least one test                                 |

## Troubleshooting

### Global setup fails with "Target page, context or browser has been closed"

**Cause**: The login page redirected unexpectedly, or the browser closed before `storageState()` was called.

**Fix**:

- Add `await page.waitForURL()` after the login action
- Check that `baseURL` in your config matches the actual server URL and protocol
- Add error handling to global setup:

```typescript
const response = await page.waitForResponse("**/api/auth/**");
if (!response.ok()) {
  throw new Error(
    `Login failed in global setup: ${response.status()} ${await response.text()}`
  );
}
```

### Tests fail with 401 Unauthorized after running for a while

**Cause**: The session token saved in `storageState` has expired.

**Fix**:

- Use the session refresh fixture pattern
- Increase token expiry in test environment configuration
- Switch to API-based login in a worker-scoped fixture

### `storageState` file is empty or contains no cookies

**Cause**: `storageState()` was called before the login response set cookies.

**Fix**:

- Wait for the post-login page to load: `await page.waitForURL('/home')`
- Verify cookies exist before saving:

```typescript
const cookies = await context.cookies();
if (cookies.length === 0) {
  throw new Error("No cookies found after login");
}
await context.storageState({ path: ".auth/session.json" });
```

### Different browsers get different cookies

**Cause**: Some auth flows set cookies with `SameSite=Strict` or use browser-specific cookie behavior.

**Fix**:

- Generate separate auth state files per browser project
- Check if your auth uses `SameSite=None; Secure` cookies that require HTTPS:

```typescript
projects: [
  {
    name: 'chromium',
    use: { ...devices['Desktop Chrome'], storageState: '.auth/chromium-session.json' },
  },
  {
    name: 'firefox',
    use: { ...devices['Desktop Firefox'], storageState: '.auth/firefox-session.json' },
  },
],
```

### Parallel tests interfere with each other's sessions

**Cause**: Multiple workers share the same test account and one worker's actions affect others.

**Fix**:

- Use per-worker test accounts: `worker-${test.info().parallelIndex}@example.com`
- Use the per-worker authentication fixture pattern
- Make tests idempotent

### OAuth mock does not work — still redirects to real provider

**Cause**: `page.route()` was registered after the navigation that triggers the OAuth redirect.

**Fix**:

- Register route handlers before any navigation: call `page.route()` before `page.goto()`
- Log the actual redirect URL to verify the pattern:

```typescript
page.on("request", (req) => {
  if (req.url().includes("oauth") || req.url().includes("accounts.provider")) {
    console.log("OAuth request:", req.url());
  }
});
```

## Related

- [fixtures-hooks.md](../core/fixtures-hooks.md) — custom fixtures for auth setup and teardown
- [configuration.md](../core/configuration.md) — `storageState`, projects, and global setup configuration
- [global-setup.md](../core/global-setup.md) — global setup patterns and project dependencies
- [network-advanced.md](network-advanced.md) — route interception patterns used in OAuth mocking
- [api-testing.md](../testing-patterns/api-testing.md) — API request context used in API-based login
- [flaky-tests.md](../debugging/flaky-tests.md) — diagnosing auth-related flakiness