fix: Output OAuth settings to config without requiring domain prefix (#957)

* fix: oauth config is output even if domainPrefix is missing

* fix: cleanup

* fix: bug where oauthClientId was not being set

* chore: update test and add changeset

Author: awsluja

.changeset/metal-radios-pay.md

@@ -0,0 +1,6 @@
+---
+'@aws-amplify/auth-construct-alpha': patch
+'@aws-amplify/client-config': patch
+---
+
+Fix bug in frontend config where oauth would not be output if domain prefix was not defined.

package-lock.json

@@ -556,6 +556,7 @@ void describe('Auth construct', () => {
             verificationMechanisms: '["EMAIL"]',
             usernameAttributes: '["EMAIL"]',
             googleClientId: 'googleClientId',
+            oauthClientId: expectedWebClientId, // same thing
             oauthDomain: `test-prefix.auth.${expectedRegion}.amazoncognito.com`,
             oauthScope: '["email","profile"]',
             oauthRedirectSignIn: 'http://callback.com',

packages/auth-construct/src/construct.test.ts

@@ -885,7 +885,7 @@ export class AmplifyAuth
         output.oauthRedirectSignOut = this.oAuthSettings.logoutUrls
           ? this.oAuthSettings.logoutUrls.join(',')
           : '';
-        output.webClientId = this.resources.userPoolClient.userPoolClientId;
+        output.oauthClientId = this.resources.userPoolClient.userPoolClientId;
         output.oauthResponseType = 'code';
       }
     }

packages/auth-construct/src/construct.ts

@@ -87,9 +87,11 @@ export class AuthClientConfigContributor implements ClientConfigContributor {
       );
     }
 
-    if (authOutput.payload.oauthDomain) {
+    if (authOutput.payload.oauthClientId) {
       authClientConfig.oauth = {};
-      authClientConfig.oauth.domain = authOutput.payload.oauthDomain;
+      if (authOutput.payload.oauthDomain) {
+        authClientConfig.oauth.domain = authOutput.payload.oauthDomain;
+      }
       parseAndAssignObject(
         authClientConfig.oauth,
         'scope',