test(integration): add tests for session_exists redirect behavior

- Add tests in sign-in-flow.test.ts for regular sign-in with existing session
- Add test in oauth-flows.test.ts for OAuth sign-in with existing session
- Verify users are redirected and remain signed in instead of seeing errors

Author: brkalow

integration/tests/oauth-flows.test.ts

@@ -256,5 +256,26 @@ testAgainstRunningApps({ withEnv: [appConfigs.envs.withLegalConsent] })(
 
       await u.page.waitForAppUrl('/protected');
     });
+
+    test('redirects when attempting OAuth sign in with existing session', async ({ page, context }) => {
+      const u = createTestUtils({ app, page, context });
+
+      // First, sign in the user via OAuth
+      await u.po.signIn.goTo();
+      await u.page.getByRole('button', { name: 'E2E OAuth Provider' }).click();
+      await u.page.getByText('Sign in to oauth-provider').waitFor();
+      await u.po.signIn.setIdentifier(fakeUser.email);
+      await u.po.signIn.continue();
+      await u.po.signIn.enterTestOtpCode();
+      await u.page.getByText('SignedIn').waitFor();
+      await u.po.expect.toBeSignedIn();
+
+      // Now attempt to sign in again via OAuth while already signed in
+      await u.po.signIn.goTo();
+      await u.page.getByRole('button', { name: 'E2E OAuth Provider' }).click();
+
+      // Should redirect and remain signed in instead of showing an error
+      await u.po.expect.toBeSignedIn();
+    });
   },
 );

integration/tests/sign-in-flow.test.ts

@@ -150,4 +150,45 @@ testAgainstRunningApps({ withEnv: [appConfigs.envs.withEmailCodes] })('sign in f
 
     await u.po.expect.toBeSignedIn();
   });
+
+  test('redirects when attempting to sign in with existing session', async ({ page, context }) => {
+    const u = createTestUtils({ app, page, context });
+
+    // First, sign in the user
+    await u.po.signIn.goTo();
+    await u.po.signIn.setIdentifier(fakeUser.email);
+    await u.po.signIn.continue();
+    await u.po.signIn.setPassword(fakeUser.password);
+    await u.po.signIn.continue();
+    await u.po.expect.toBeSignedIn();
+
+    // Now attempt to go to sign-in page again while already signed in
+    await u.po.signIn.goTo();
+
+    // User should be redirected and remain signed in instead of seeing an error
+    await u.po.expect.toBeSignedIn();
+  });
+
+  test('redirects when attempting to sign in again with instant password and existing session', async ({
+    page,
+    context,
+  }) => {
+    const u = createTestUtils({ app, page, context });
+
+    // First, sign in the user
+    await u.po.signIn.goTo();
+    await u.po.signIn.signInWithEmailAndInstantPassword({ email: fakeUser.email, password: fakeUser.password });
+    await u.po.expect.toBeSignedIn();
+
+    // Clear the page to go back to sign-in
+    await u.page.goToRelative('/');
+    await u.po.expect.toBeSignedIn();
+
+    // Attempt to sign in again with instant password
+    await u.po.signIn.goTo();
+    await u.po.signIn.signInWithEmailAndInstantPassword({ email: fakeUser.email, password: fakeUser.password });
+
+    // Should redirect and remain signed in without error
+    await u.po.expect.toBeSignedIn();
+  });
 });