Added unit tests for settings business logic elements

test/settings/services/SettingsService.test.js

@@ -0,0 +1,46 @@
+import SettingsService from '../../../src/settings/services/SettingsService';
+
+describe('SettingsService', () => {
+  const settings = { foo: 'bar' };
+  const createService = (withSettings = true) => {
+    const storageMock = {
+      set: jest.fn(),
+      get: jest.fn(() => withSettings ? settings : undefined),
+    };
+    const service = new SettingsService(storageMock);
+
+    return [ service, storageMock ];
+  };
+
+  afterEach(jest.resetAllMocks);
+
+  describe('loadSettings', () => {
+    it.each([
+      [ false, {}],
+      [ true, settings ],
+    ])('returns result if found in storage', (withSettings, expectedResult) => {
+      const [ service, storageMock ] = createService(withSettings);
+
+      const result = service.loadSettings();
+
+      expect(result).toEqual(expectedResult);
+      expect(storageMock.get).toHaveBeenCalledTimes(1);
+      expect(storageMock.set).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('updateSettings', () => {
+    it.each([
+      [ false, { hi: 'goodbye' }, { hi: 'goodbye' }],
+      [ true, { hi: 'goodbye' }, { foo: 'bar', hi: 'goodbye' }],
+      [ true, { foo: 'goodbye' }, { foo: 'goodbye' }],
+    ])('appends provided data to existing settings', (withSettings, settingsToUpdate, expectedResult) => {
+      const [ service, storageMock ] = createService(withSettings);
+
+      service.updateSettings(settingsToUpdate);
+
+      expect(storageMock.get).toHaveBeenCalledTimes(1);
+      expect(storageMock.set).toHaveBeenCalledWith(expect.anything(), expectedResult);
+    });
+  });
+});