Override Flags SDK for Playwright tests

example.spec.ts

import { test, expect } from '@playwright/test';
import { setFlagOverrides } from "./y";

test.describe('flags off', () => {
  setFlagOverrides(test, {
    'example-flag': false,
    'another-example-flag': true,
  });

  test('should do something', async ({ page }) => {
    const response = await page.goto('/');
    expect(response?.status()).toBe(200);

    // ... your test code here
  });
});

set-flag-overrides.ts

import type { test as base } from '@playwright/test';
import { encryptOverrides } from 'flags';

const FEATURE_FLAGS_COOKIE_NAME = 'vercel-flag-overrides';

/**
 * Sets flag overrides that work with the `flags` package.
 *
 * @param test - The test instance.
 * @param flags - The flags to override.
 */
export function setFlagOverrides(
  test: typeof base,
  flags: Record<string, unknown>,
): void {
  const flagsSecret = process.env.FLAGS_SECRET;
  const baseUrl = process.env.BASE_URL;
  if (!flagsSecret) {
    throw new Error(
      'Cannot call setFlags without `FLAGS_SECRET` environment variable defined.',
    );
  }

  test.beforeEach(async ({ context }) => {
    const encryptedFlags = await encryptOverrides(flags, flagsSecret);
    await context.addCookies([
      {
        name: FEATURE_FLAGS_COOKIE_NAME,
        value: encryptedFlags,
        path: '/',
        domain: new URL(baseUrl).hostname,
      },
    ]);
  });
}