Generate fake hashrate to test client & server resources

[hahahafr]

In a controlled environment on both side (mining-client & mining-server), how can one generate fake hashrate on the client side, get it accepted by the server as valid to generate fake bitcoins, so one could test the hardware resources of the server (and the client as well).

[Graet]

testnet in a box http://sourceforge.net/projects/bitcoin/files/Bitcoin/testnet-in-a-box/
https://en.bitcoin.it/wiki/Testnet

[hahahafr]

So if a mining-server is linked to a bitcoind having a network difficulty of 1, the mining-client will send way more share and the mining-server accepting way more. But is it possible to say generate 1 TH/s of fake share and get them to accept by the server, without having to fiddle with the mining-server source code too much.

I wonder how it was done when testing PoolServerJ performance compared to pushpool: http://web.archive.org/web/20111129134439/http://poolserverj.org/performance-testing/