fix(oauth-desktop): Send canLinkAccount if service=sync

Because:
* We were only checking for desktopv3 in this case and want to check for desktopv3 and oauth desktop

This commit:
* Modifies the condition to call firefox.fxaCanLinkAccount, updates tests

fixes FXA-10328

packages/fxa-content-server/app/scripts/models/reliers/oauth.js

@@ -218,7 +218,10 @@ var OAuthRelier = Relier.extend({
 
     // OAuth reliers are not allowed to specify a service. `service`
     // is used in the verification flow, it'll be set to the `client_id`.
-    if (this.getSearchParam('service')) {
+    if (
+      this.getSearchParam('service') &&
+      this.getSearchParam('service') !== 'sync'
+    ) {
       throw OAuthErrors.toInvalidParameterError('service');
     }
   },

packages/fxa-settings/src/pages/Signin/container.test.tsx

@@ -71,14 +71,18 @@ function mockSyncDesktopV3Integration() {
     getService: () => 'sync',
     isSync: () => true,
     wantsKeys: () => true,
+    data: { service: 'sync' },
   } as Integration;
 }
-function mockSyncOAuthIntegration() {
+function mockSyncOAuthIntegration(
+  { data }: { data?: { service?: string } } = { data: { service: 'sync' } }
+) {
   integration = {
     type: IntegrationType.OAuth,
     getService: () => 'sync',
     isSync: () => true,
     wantsKeys: () => true,
+    data,
   } as Integration;
 }
 
@@ -88,6 +92,7 @@ function mockWebIntegration() {
     getService: () => MozServices.Default,
     isSync: () => false,
     wantsKeys: () => false,
+    data: {},
   } as Integration;
 }
 
@@ -617,9 +622,24 @@ describe('signin container', () => {
         });
       });
       it('is not called when conditions are not met (oauth integration)', async () => {
+        mockSyncOAuthIntegration({ data: {} });
+        (firefox.fxaCanLinkAccount as jest.Mock).mockImplementationOnce(
+          async () => ({
+            ok: true,
+          })
+        );
+        render([mockGqlAvatarUseQuery()]);
+
+        await waitFor(async () => {
+          await currentSigninProps?.beginSigninHandler(
+            MOCK_EMAIL,
+            MOCK_PASSWORD
+          );
+          expect(firefox.fxaCanLinkAccount).not.toHaveBeenCalled();
+        });
+      });
+      it('calls fxaCanLinkAccount when conditions are met (oauth integration)', async () => {
         mockSyncOAuthIntegration();
-        // TODO: when desktop moves to oauth, we must update this logic and test
-        mockUseValidateModule();
         (firefox.fxaCanLinkAccount as jest.Mock).mockImplementationOnce(
           async () => ({
             ok: true,

packages/fxa-settings/src/pages/Signin/container.tsx

@@ -10,7 +10,6 @@ import {
   useFtlMsgResolver,
   useConfig,
   useSession,
-  isSyncDesktopV3Integration,
   useSensitiveDataClient,
 } from '../../models';
 import { MozServices } from '../../lib/types';
@@ -242,7 +241,9 @@ const SigninContainer = ({
       // warning. The browser will automatically respond with { ok: true } without
       // prompting the user if it matches the email the browser has data for.
       if (
-        isSyncDesktopV3Integration(integration) &&
+        // NOTE, SYNC-4408 OAuth desktop needs to add `service=sync` as a query parameter
+        // for this to work for OAuth desktop
+        integration.data.service === 'sync' &&
         queryParamModel.hasLinkedAccount === undefined
       ) {
         const { ok } = await firefox.fxaCanLinkAccount({ email });