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);
+    }
+  });
+});

tests/mocks/ChromeEvent.ts

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+export default class ChromeEvent<T extends Function> implements chrome.events.Event<T> {
+    addListener = vi.fn();
+    getRules = vi.fn();
+    hasListener = vi.fn();
+    removeRules = vi.fn();
+    addRules = vi.fn();
+    removeListener = vi.fn();
+    hasListeners = vi.fn();
+}

tests/mocks/ChromeLocalStorageArea.ts

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+import ChromeStorageArea from "$tests/mocks/ChromeStorageArea";
+
+export class ChromeLocalStorageArea extends ChromeStorageArea implements chrome.storage.LocalStorageArea {
+    QUOTA_BYTES = 100000;
+}

tests/mocks/ChromeStorageArea.ts

@@ -0,0 +1,71 @@
+import ChromeEvent from "./ChromeEvent";
+
+type ChangedEventCallback = (changes: chrome.storage.StorageChange) => void
+
+export default class ChromeStorageArea implements chrome.storage.StorageArea {
+  #mockedData: Record<string, any> = {};
+
+  getBytesInUse = vi.fn();
+  clear = vi.fn((): Promise<void> => {
+    return new Promise(resolve => {
+      this.#mockedData = {};
+      resolve();
+    })
+  });
+  set = vi.fn((...args: any[]): Promise<void> => {
+    return new Promise((resolve, reject) => {
+      this.#mockedData = Object.assign(this.#mockedData, args[0]);
+      resolve();
+    })
+  });
+  remove = vi.fn((...args: any[]): Promise<void> => {
+    return new Promise((resolve, reject) => {
+      const key = args[0];
+
+      if (typeof key === 'string') {
+        delete this.#mockedData[key];
+        resolve();
+      }
+
+      reject(new Error('This behavior is not mocked!'));
+    });
+  });
+  get = vi.fn((...args: any[]) => {
+    return new Promise((resolve, reject) => {
+      const key = args[0];
+
+      if (!key) {
+        resolve(this.#mockedData);
+        return;
+      }
+
+      if (typeof key === 'string') {
+        resolve({[key]: this.#mockedData[key]});
+        return;
+      }
+
+      if (Array.isArray(key)) {
+        resolve(
+          (key as string[]).reduce((entries, key) => {
+            entries[key] = this.#mockedData[key];
+            return entries;
+          }, {} as Record<string, any>)
+        );
+        return;
+      }
+
+      reject(new Error('This behavior is not implemented by the mock.'));
+    });
+  });
+  setAccessLevel = vi.fn();
+  onChanged = new ChromeEvent<ChangedEventCallback>();
+  getKeys = vi.fn();
+
+  insertMockedData(data: Record<string, any>) {
+    this.#mockedData = data;
+  }
+
+  get mockedData(): Record<string, any> {
+    return this.#mockedData;
+  }
+}