gen option on bitcoind: testing Can you actually generate "test" coins using bitcoind and testnet?

I mean, in a standalone test environment, can the generation of "simulated" BTC be done and with very short test blockchain be done in a very short time?
Testnet is not a standalone test environment. It's an actual distributed block chain like the main chain. Only, because few people are mining on testnet, the difficulty is quite low.

So yes, you can generate test coins on testnet.

Beside this, it is possible to create a very own standalone test environment, but it would require you to edit the source code. Specifically, you will need to change the (hard coded) genesis block and most probably remove the peer seeds because you don't want to bother mainnet or testnet users with your own blocks.