Added initial implementation of mocks for chrome StorageArea, adding first tests for storage helper

tests/lib/browser/StorageHelper.spec.ts

@@ -0,0 +1,40 @@
+import ChromeStorageArea from "$tests/mocks/ChromeStorageArea";
+import StorageHelper from "$lib/browser/StorageHelper";
+import { expect } from "vitest";
+
+describe('StorageHelper', () => {
+  let storageAreaMock: ChromeStorageArea;
+  let storageHelper: StorageHelper;
+
+  beforeEach(() => {
+    storageAreaMock = new ChromeStorageArea();
+    storageHelper = new StorageHelper(storageAreaMock);
+  });
+
+  it("should return value when data exists", async () => {
+    const key = 'existingKey';
+    const value = 'test value';
+
+    storageAreaMock.insertMockedData({[key]: value});
+
+    expect(await storageHelper.read(key)).toBe(value);
+  });
+
+  it('should return default when data is not present', async () => {
+    const fallbackValue = 'fallback';
+
+    expect(await storageHelper.read('nonexistent', fallbackValue)).toBe(fallbackValue);
+  });
+
+  it('should treat falsy values as existing values', async () => {
+    const falsyValues = [false, '', 0];
+    const key = 'testedKey';
+    const fallbackValue = 'fallback';
+
+    for (let testedValue of falsyValues) {
+      storageAreaMock.insertMockedData({[key]: testedValue});
+
+      expect(await storageHelper.read(key, fallbackValue)).toBe(testedValue);
+    }
+  });
+});