test: fix createCustomToken test

Author: rbellens

test/app_test.dart

@@ -204,7 +204,7 @@ void main() {
         var app = admin.initializeApp(mocks.appOptions);
         expect(app.options.credential, TypeMatcher<ServiceAccountCredential>());
         expect(app.options.databaseUrl, 'https://databaseName.firebaseio.com');
-        expect(app.options.projectId, null);
+        expect(app.options.projectId, 'project_id');
         expect(app.options.storageBucket, 'bucketName.appspot.com');
       });
 

test/auth_test.dart

@@ -788,7 +788,7 @@ void main() {
         var token = await auth.createCustomToken(uid, {'isAdmin': true});
         var decodedToken = IdToken.unverified(token);
         expect(decodedToken.claims['uid'], uid);
-        expect(decodedToken.claims['isAdmin'], isTrue);
+        expect(decodedToken.claims['claims']['isAdmin'], isTrue);
 
         var jwks = JsonWebKeySet.fromJson(json.decode(
             File('test/resources/openid-jwks.json').readAsStringSync()));

test/resources/mocks.dart

@@ -13,6 +13,7 @@ var storageBucket = 'bucketName.appspot.com';
 var credential = FirebaseAdmin.instance.testCredentials();
 
 var appOptions = AppOptions(
+  projectId: projectId,
   credential: credential,
   databaseUrl: databaseURL,
   storageBucket: storageBucket,