For debugging purposes one can add
eosio::print instructions to a contract.
These printed messages can be read in Hydra by accessing the transaction trace object that is returned when executing transactions on the account contract object.
For a given contract with a
hello action that prints the username a test could be written as follows:
Console prints are recorded per action
There is no single console output for a transaction, instead, each action carries its own console output in the corresponding action trace.
Make sure to access the correct action trace when dealing with inline actions or notifications to other contracts.
For example, when transferring tokens using the
eosio.token contract three action traces are created, one for the initial action on the
eosio.token contract and two for the notifications sent to the sender and receiver.