[UXP-170] fix test

Author: Andrea Barbasso

src/app/shared/object-detail/my-dspace-result-detail-element/item-detail-preview/item-detail-preview-field/item-detail-preview-field.component.spec.ts

@@ -90,9 +90,9 @@ describe('ItemDetailPreviewFieldComponent', () => {
     fixture.detectChanges();
   });
 
-  it('should display dc.title value', () => {
-    const span = fixture.debugElement.query(By.css('span'));
-    expect(span.nativeElement.innerHTML).toContain('This is just another title');
+  it('should render a ds-markdown-viewer', () => {
+    const mdViewer = fixture.debugElement.query(By.css('ds-markdown-viewer'));
+    expect(mdViewer).not.toBeNull();
   });
 
   it('should display placeholder when metadata has no value', () => {