functional_daemon_test does not pass on first test run on local setup

[LeoNero]

functional_daemon_test, defined inside tests/rpc.rs does not pass when running cargo test the first time WHEN there are no blocks in the regtest network, but it works if there is.

Also, the test pass for the test workflow in the repository, probably because the tests run concurrently and the wallet test creates blocks before the daemon test runs.

As a solution, a block can first be created. Or, if the intention is to test a possible failure, then just test the Error returned.

This issue is related to #48

---

Error returned by cargo test --tests rpc:

'functional_daemon_test' panicked at 'called `Result::unwrap()` on an `Err` value: Server error: Requested block height: 1 greater than current top block height: 0

Line that causes the error is line 27 https://github.com/monero-ecosystem/monero-rpc-rs/blob/master/tests/rpc.rs#L27

[LeoNero]

I did more debugging and functional_daemon_test always pass on v0.17.3.2 but almost always does not pass on master.

[LeoNero]

Cool, on v0.17.3, it returns:

{
  "id": "0",
  "jsonrpc": "2.0",
  "result": "0000000000000000000000000000000000000000000000000000000000000000"
}

On master:

{                                                                                                                                   
    "error": {                                                                                                                      
        "code": -2,                                                                                                                 
        "message": "Requested block height: 1 greater than current top block height: 0"                                             
    },                                                                                                                             
    "id": "0",                                                                                                                     
    "jsonrpc": "2.0"                                                                                                               
}

Edit: looking at the code, it ends up to a call to BlockchainLMDB::height(), defined at master https://github.com/monero-project/monero/blob/8f48f464957c875af3183cd9d35769592e1aef48/src/blockchain_db/lmdb/db_lmdb.cpp#L2917 and v0.17.3.2 at https://github.com/monero-project/monero/blob/424e4de16b98506170db7b0d7d87a79ccf541744/src/blockchain_db/lmdb/db_lmdb.cpp#L2952

They are the same, so probably it was a change to lmdb's internals?

[LeoNero]

Ok, I saw what is going on. The last commit on master (8f48f464957c875af3183cd9d35769592e1aef48) has the same of v0.17.32 for the function core_rpc_server::on_getblockhash, but my local branch was at 9750e1fa103539b3e533455500610aae76e253a5 which has a different implementation.
See: https://github.com/monero-project/monero/blob/8f48f464957c875af3183cd9d35769592e1aef48/src/rpc/core_rpc_server.cpp#L1701, https://github.com/monero-project/monero/blob/424e4de16b98506170db7b0d7d87a79ccf541744/src/rpc/core_rpc_server.cpp#L1663, and https://github.com/monero-project/monero/blob/9750e1fa103539b3e533455500610aae76e253a5/src/rpc/core_rpc_server.cpp#L1706

Those changes are related to monero-project/monero#7936, monero-project/monero#7937, and monero-project/monero#8384

[LeoNero]

Closing now that the debug is over :)