feat: duplicate error behavior in fake storage service

libs/common/spec/fake-storage.service.ts

@@ -8,6 +8,8 @@ import {
 } from "../src/platform/abstractions/storage.service";
 import { StorageOptions } from "../src/platform/models/domain/storage-options";
 
+const INTERNAL_KEY = "__internal__";
+
 export class FakeStorageService implements AbstractStorageService, ObservableStorageService {
   private store: Record<string, unknown>;
   private updatesSubject = new Subject<StorageUpdate>();
@@ -63,13 +65,28 @@ export class FakeStorageService implements AbstractStorageService, ObservableSto
     this.mock.has(key, options);
     return Promise.resolve(this.store[key] != null);
   }
-  save<T>(key: string, obj: T, options?: StorageOptions): Promise<void> {
-    // FIXME: Verify that this floating promise is intentional. If it is, add an explanatory comment and ensure there is proper error handling.
-    // eslint-disable-next-line @typescript-eslint/no-floating-promises
-    this.mock.save(key, obj, options);
+  async save<T>(key: string, obj: T, options?: StorageOptions): Promise<void> {
+    // These exceptions are copied from https://github.com/sindresorhus/conf/blob/608adb0c46fb1680ddbd9833043478367a64c120/source/index.ts#L193-L203
+    // which is a library that is used by `ElectronStorageService`. We add them here to ensure that the behavior in our testing mirrors the real world.
+    if (typeof key !== "string" && typeof key !== "object") {
+      throw new TypeError(
+        `Expected \`key\` to be of type \`string\` or \`object\`, got ${typeof key}`,
+      );
+    }
+
+    if (typeof key !== "object" && obj === undefined) {
+      throw new TypeError("Use `delete()` to clear values");
+    }
+
+    if (this._containsReservedKey(key)) {
+      throw new TypeError(
+        `Please don't use the ${INTERNAL_KEY} key, as it's used to manage this module internal operations.`,
+      );
+    }
+
+    await this.mock.save(key, obj, options);
     this.store[key] = obj;
     this.updatesSubject.next({ key: key, updateType: "save" });
-    return Promise.resolve();
   }
   remove(key: string, options?: StorageOptions): Promise<void> {
     // FIXME: Verify that this floating promise is intentional. If it is, add an explanatory comment and ensure there is proper error handling.
@@ -79,4 +96,20 @@ export class FakeStorageService implements AbstractStorageService, ObservableSto
     this.updatesSubject.next({ key: key, updateType: "remove" });
     return Promise.resolve();
   }
+
+  private _containsReservedKey(key: string | Partial<unknown>): boolean {
+    if (typeof key === "object") {
+      const firsKey = Object.keys(key)[0];
+
+      if (firsKey === INTERNAL_KEY) {
+        return true;
+      }
+    }
+
+    if (typeof key !== "string") {
+      return false;
+    }
+
+    return false;
+  }
 }