In-memory database

[hasufell]

PostgreSQL is quite heavy to set up for e.g. integration tests. There could be an option to run everything in-memory.

Or... sqlite.

Related: cardano-foundation/cardano-wallet#2249

[hasufell]

It seems there's already some support for it, but it isn't exposed in the cli:

smash/src/Lib.hs

Lines 129 to 137 in d335fed

	runAppStubbed :: Configuration -> IO ()
	runAppStubbed configuration = do
	let port = cPortNumber configuration
	let settings =
	setPort port $
	setBeforeMainLoop (hPutStrLn stderr ("listening on port " ++ show port)) $
	defaultSettings
	runSettings settings =<< mkAppStubbed configuration

[hasufell]

I actually think the way forward is SQLite. I've done some hacking on that in a local branch. The reasoning is:

1. it might be interesting for end-users: postgres is a heavy dependency
2. SQLite can be run in-memory for integration tests, which means I have more coverage for the smash implementation compared to the stubbed Configuration (since we still run through the persistent framework)

[ksaric]

I have some additional ideas about how to make this even nicer.
Some of this will be covered by the upcoming issue creatively called "Add tests for the existing functionality" 😄

Will report back to you, should be handled in this sprint as well.