Policy/fee asset doesn't seem to be set in the src/test unit-tests. I noticed this in txvalidationcache_tests.cpp, where the fee output was discarded when the tx was entered in the mempool as in AcceptToMemoryPoolWorker the following returns 0:
CAmount nFees = tx.GetFee()[policyAsset];
Although it doesn't break anything as zero fees are allowed, it might hide intended functionality if something changed. Do you think it would make sense to add this in the test_bitcoin configuration?