Parity PoA private chain - notes

[pcppcp]

Today I've tried to make Parity's dev chain work. My idea was it'd be nice to have a real chain/RPC interface to play with and run CI on. Ropsten is unfortunately too slow to run the tests on. Following are some notes to myself or anyone brave enough to play with it.

• InstaSeal engine creates a block whenever a transaction appears. uRaiden test fixtures need to be adapted to support mining, and a greenlet that creates a tx every now and then must be spawned (some of the tests do not wait_for_blocks but rather wait for txhash.
• the devchain contains an account preloaded with a lot of ether. Supposedly, the passphrase should be an empty string. However, personal_unlockAccount sometimes doesn't work. Commandline options that unlock the account sometimes fail too.
• over the time gas limit in a block decreases to a point where it's impossible to deploy the contract. It should be possible to set a custom value, but I haven't managed to create a genesis file that'd work - Parity doesn't see the test account and private key import fails.
• remedy to the problems above is usually rm -rf
• did I mention Parity coredumps on ^C?

Conclusion? Parity's private devchain is a pile of crap. Maybe I've messed up something when compiling (I've used last stable/v1.8.6), but frequent googling revealed I am not alone experiencing these bugs.