Yeah, we can see that the MockPageManager.copy is not implemented.
@Override
294 public Page copy(final Page page, final String destination, final String beforeName, final boolean shallow,
295 final boolean resolveConflict) {
296 throw new UnsupportedOperationException();
297 }
https://wcm.io/testing/aem-mock//xref/io/wcm/testing/mock/aem/MockPageManager.html
What is another way to test this?