test: send cookies via an embedded iframe (#17036)

tests/library/browsercontext-cookies.spec.ts

@@ -320,3 +320,32 @@ it('should add cookies with an expiration', async ({ context }) => {
     expires: -42,
   }])).rejects.toThrow(/Cookie should have a valid expires/);
 });
+
+it('should be able to send third party cookies via an iframe', async ({ browser, httpsServer, browserName }) => {
+  it.fixme(browserName === 'firefox' || browserName === 'webkit');
+  it.info().annotations.push({ type: 'issue', description: 'https://github.com/microsoft/playwright/issues/16937' });
+
+  const context = await browser.newContext({
+    ignoreHTTPSErrors: true,
+  });
+  try {
+    const page = await context.newPage();
+    await page.goto(httpsServer.EMPTY_PAGE);
+    await context.addCookies([{
+      domain: new URL(httpsServer.CROSS_PROCESS_PREFIX).hostname,
+      path: '/',
+      name: 'cookie1',
+      value: 'yes',
+      httpOnly: true,
+      secure: true,
+      sameSite: 'None'
+    }]);
+    const [response] = await Promise.all([
+      httpsServer.waitForRequest('/grid.html'),
+      page.setContent(`<iframe src="${httpsServer.CROSS_PROCESS_PREFIX}/grid.html"></iframe>`)
+    ]);
+    expect(response.headers['cookie']).toBe('cookie1=yes');
+  } finally {
+    await context.close();
+  }
+});