add test for data-overlayscrollbars-initialize attribute

packages/overlayscrollbars-ngx/test/overlayscrollbars.component.spec.ts

@@ -105,11 +105,13 @@ describe('OverlayscrollbarsNgxComponent', () => {
       expect(OverlayScrollbars.valid(component.instance())).toBe(true);
     });
 
-    it('has data-overlayscrollbars attribute', async () => {
+    it('has data-overlayscrollbars-initialize', async () => {
       const testFixture = TestBed.createComponent(Test);
-      const testOsComponent = testFixture.debugElement.children[0];
+      const testComponent = testFixture.nativeElement as HTMLElement;
 
-      expect(testOsComponent.attributes['data-overlayscrollbars']).toBe('');
+      testFixture.detectChanges();
+
+      expect(testComponent?.querySelector('[data-overlayscrollbars-initialize]')).toBeTruthy();
     });
 
     it('has children', async () => {

packages/overlayscrollbars-react/test/OverlayScrollbarsComponent.test.tsx

@@ -42,6 +42,12 @@ describe('OverlayScrollbarsComponent', () => {
       expect(OverlayScrollbars.valid(osInstance)).toBe(true);
     });
 
+    test('data-overlayscrollbars-initialize', async () => {
+      const { container } = render(<OverlayScrollbarsComponent />);
+
+      expect(container.querySelector('[data-overlayscrollbars-initialize]')).toBeTruthy();
+    });
+
     test('children', () => {
       const { container } = render(
         <OverlayScrollbarsComponent>

packages/overlayscrollbars-vue/test/OverlayScrollbarsComponent.test.tsx

@@ -40,6 +40,12 @@ describe('OverlayScrollbarsComponent', () => {
       expect(OverlayScrollbars.valid(osInstance)).toBe(true);
     });
 
+    test('data-overlayscrollbars-initialize', async () => {
+      const { container } = render(OverlayScrollbarsComponent);
+
+      expect(container.querySelector('[data-overlayscrollbars-initialize]')).toBeTruthy();
+    });
+
     test('children', () => {
       const { container } = render(OverlayScrollbarsComponent, {
         slots: { default: 'hello <span>vue</span>' },