Use default param (review feedback).

Author: yuchenshi

packages/rules-unit-testing/src/impl/test_environment.ts

@@ -200,9 +200,8 @@ class RulesTestContextImpl implements RulesTestContext {
     );
     return database;
   }
-  storage(bucketUrl?: string): firebase.storage.Storage {
+  storage(bucketUrl = `gs://${this.projectId}`): firebase.storage.Storage {
     assertEmulatorRunning(this.emulators, 'storage');
-    bucketUrl ||= `gs://${this.projectId}`;
     const storage = this.getApp().storage(bucketUrl);
     storage.useEmulator(
       this.emulators.storage.host,