public void testExecutePredicateWithResults() {
   Iterable<Datacenter> datacenters =
       strategy.execute(DatacenterPredicates.name(env.datacenter.getName()));
   assertNotNull(datacenters);
   assertEquals(size(datacenters), 1);
 }
 public void testExecutePredicateWithoutResults() {
   Iterable<Datacenter> datacenters = strategy.execute(DatacenterPredicates.name("UNEXISTING"));
   assertNotNull(datacenters);
   assertEquals(size(datacenters), 0);
 }