public void Union_Different_Site ()
{
SiteIdentityPermission sip1 = new SiteIdentityPermission (GoodSites [0]);
SiteIdentityPermission sip2 = new SiteIdentityPermission (GoodSites [1]);
SiteIdentityPermission result = (SiteIdentityPermission)sip1.Union (sip2);
// it's not possible to return many sites using the Site property so it throws
Assert.IsNull (result.Site);
}