so you just test the following:
summoner logs off, summoned logs off, summoner leaves shard and runs summon/return commands from other shards, summoned leaves shard
each of those in combination with all commands
summon --> restart server --> have only summoned logon and do stuff
summon --> restart server --> have only summoner logon and attempt to resummon/return/do stuff
ensure repearling a summoned player works properly and the cache is cleared up, so resummoning by another player works
ensure returning works after both summoner and summoned have crossed a shard border
so you just test the following: summoner logs off, summoned logs off, summoner leaves shard and runs summon/return commands from other shards, summoned leaves shard each of those in combination with all commands summon --> restart server --> have only summoned logon and do stuff summon --> restart server --> have only summoner logon and attempt to resummon/return/do stuff ensure repearling a summoned player works properly and the cache is cleared up, so resummoning by another player works ensure returning works after both summoner and summoned have crossed a shard border