test: add critical flow test for on-prem login redirect [WPB-25319]

apps/webapp/test/e2e_tests/backend/brigRepository.e2e.ts

@@ -251,4 +251,31 @@ export class BrigRepositoryE2E {
       },
     );
   }
+
+  public async claimDomain(domain: string) {
+    await this.axiosInstance.put(
+      `i/domain-registration/${domain}`,
+      {
+        backend: {
+          config_url: new URL('deeplink.json', process.env.FEDERATION_BACKEND_URL),
+          webapp_url: process.env.FEDERATION_WEBAPP_URL,
+        },
+        domain_redirect: 'backend',
+        team_invite: 'not-allowed',
+      },
+      {
+        headers: {
+          Authorization: `Basic ${BASIC_AUTH}`,
+        },
+      },
+    );
+  }
+
+  public async deleteDomainClaim(domain: string) {
+    await this.axiosInstance.delete(`i/domain-registration/${domain}`, {
+      headers: {
+        Authorization: `Basic ${BASIC_AUTH}`,
+      },
+    });
+  }
 }

apps/webapp/test/e2e_tests/specs/CriticalFlow/onPremLoginRedirect-TC-8757.spec.ts

@@ -0,0 +1,65 @@
+/*
+ * Wire
+ * Copyright (C) 2025 Wire Swiss GmbH
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see http://www.gnu.org/licenses/.
+ *
+ */
+
+import {expect, test} from '../../test.fixtures';
+import {PageManager} from '../../pageManager';
+import {faker} from '@faker-js/faker';
+
+const ON_PREM_WEBAPP_URL = 'https://webapp.anta.wire.link';
+
+test.describe('On Prem Login Redirect Flow', () => {
+  let domain: string;
+  let email: string;
+
+  test.beforeEach(async ({api}) => {
+    domain = faker.internet.domainName();
+    email = `redirect-user@${domain}`;
+
+    await test.step('Claim domain and configure on-prem redirect', async () => {
+      await api.brig.claimDomain(domain);
+    });
+  });
+
+  test('On Prem Login Redirect', {tag: ['@TC-8757', '@regression']}, async ({context, createPage}) => {
+    const page = await createPage(context);
+    const pageManager = PageManager.from(page);
+    const {pages} = pageManager.webapp;
+
+    await test.step('Open login page and enter email with claimed domain', async () => {
+      await pageManager.openSSOPage();
+      await pages.singleSignOn().enterEmailOnSSOPage(email);
+    });
+
+    await test.step('Verify connect-to-organization backend dialog is shown', async () => {
+      await expect(page.getByText("Connect to your organization's backend?")).toBeVisible();
+      await expect(page.getByText(ON_PREM_WEBAPP_URL)).toBeVisible();
+    });
+
+    await test.step('Click connect and verify redirect to on-prem webapp', async () => {
+      await page.getByRole('button', {name: 'Connect'}).click();
+      await expect(page).toHaveURL(new RegExp(String.raw`${ON_PREM_WEBAPP_URL}`), {timeout: 20_000});
+    });
+  });
+
+  test.afterEach(async ({api}) => {
+    await test.step('Delete claimed domain registration', async () => {
+      await api.brig.deleteDomainClaim(domain);
+    });
+  });
+});