Add comprehensive tests for vac-optimizer application

Co-authored-by: THoguet <61246905+THoguet@users.noreply.github.com>

src/app/services/calendar-settings-service.spec.ts

@@ -1,16 +1,33 @@
 import { TestBed } from '@angular/core/testing';
-
+import { provideZonelessChangeDetection } from '@angular/core';
 import { CalendarSettingsService } from './calendar-settings-service';
 
 describe('CalendarSettingsService', () => {
 	let service: CalendarSettingsService;
 
 	beforeEach(() => {
-		TestBed.configureTestingModule({});
+		TestBed.configureTestingModule({
+			providers: [provideZonelessChangeDetection()],
+		});
 		service = TestBed.inject(CalendarSettingsService);
 	});
 
 	it('should be created', () => {
 		expect(service).toBeTruthy();
 	});
+
+	it('should initialize with default values', () => {
+		expect(service.showWeekNumbers()).toBe(false);
+		expect(service.samediMalin()).toBe(true);
+	});
+
+	it('should allow updating showWeekNumbers', () => {
+		service.showWeekNumbers.set(true);
+		expect(service.showWeekNumbers()).toBe(true);
+	});
+
+	it('should allow updating samediMalin', () => {
+		service.samediMalin.set(false);
+		expect(service.samediMalin()).toBe(false);
+	});
 });