php-src/Zend/tests/gc_005.phpt

--TEST--
GC 005: Simple object cycle
--INI--
zend.enable_gc=1
--FILE--
<?php
$a = new stdClass();
$a->a = $a;
var_dump($a);
unset($a);
var_dump(gc_collect_cycles());
echo "ok\n"
?>
--EXPECTF--
object(stdClass)#%d (1) {
  ["a"]=>
  *RECURSION*
}
int(1)
ok