Resolving TxId in Mockchain

[koslambrou]

Issue

As a user of the Mockchain in testing, I want to be able to easily retrieve the Tx given some TxId.

Currently, we can do this by writing the following function:

resolveTxIdsMockchain ::
  ( MonadError (TestError e) m
  , MonadMockchain m
  )
  => [C.TxId]
  -> m [C.Tx C.ConwayEra]
resolveTxIdsMockchain txIds = do
  txs <- getTxs
  let indexedTxs = Map.fromList $ fmap (\tx -> (C.getTxId $ C.getTxBody tx, tx)) txs
  traverse (\txId -> failOnNothing "Could not find TxId in Mockchain transactions" $ Map.lookup txId indexedTxs) txIds

However, that function is inefficient as we need to query all transactions, then manually index them by TxId.

Possible solution

Add in the MockchainState datatype the field Map TxId Tx, and provide a function to query that (similar to what we do with mcsDatums).