Total and available balance are reported as 0 until transaction gets into ledger

[piotr-iohk]

Release	Operating System	Cause
next	Linux	Code v Configuration v Environment v Human v Unknown

Context

Steps to Reproduce

0. start cadrano-http-bridge and server

$ cardano-http-bridge start --template testnet --port 8080
$ export NETWORK=testnet && cardano-wallet server

1. Create two wallets (get some funds to one of the wallet's from the faucet - https://webdevc.iohk.io/cardano/faucet/)
2. Send transaction from one wallet to another (via API or CLI)

cardano-wallet transaction create 617963656a40...22af90400 --payment 22@2cWKMJemoBahXP5nbxG1...XuDjkLJUNQGCbw36NVGmuj

or

curl  -vX POST http://localhost:8090/v2/wallets/617963656a40...22af90400/transactions \
  -H "Content-Type: application/json; charset=utf-8" \
  -d '{
"payments": [
{
	"address": "2cWKMJemoBajj...GhUbaes8Yp3KbnocL",
	"amount": {
			  "quantity": 10,
			  "unit": "lovelace"
			}
} ], 
 "passphrase": "Secure Passphrase"
}' | jq

3. Immediately after posting the transaction (via API or CLI) the source wallet reports balance = 0 (total and available) until the transaction gets in the ledger.
   Verify with: curl -vX GET http://localhost:8090/v2/wallets | jq

Expected behavior

Total balance should NOT be reported as 0 after posting a transaction.
Available balance might be dropping to 0 (Since there may be one UTxO, which is used during the transaction)

Actual behavior

After posting the transaction (via API or CLI) the source wallet reports balance = 0 (total and available) until the transaction gets in the ledger (namely until this is reported on cardano-wallet server log: [DEBUG] : - +0.000010 in ledger since 47.5487). After that the balance seems to be reported correctly, but for couple of seconds (~ 10-45 sec) the balance is 0, which can be somewhat misleading...

---

Resolution Plan

• Trying to reproduce
• Review code in charge of adding a tx in the ledger and tracing back the possible source of the bug
• Turns out the calculation of the change UTxO was completely off (and wildly different from the specification). Fixing this solves the bug.

PR

Number	Base
#292	master

QA

• I've added a few assertions in Scenario/Transactions to capture the bug described above (and I could see the test fail as expected): https://github.com/input-output-hk/cardano-wallet/blob/master/lib/http-bridge/test/integration/Test/Integration/Scenario/Transactions.hs#L73-L97

• Then, reviewed the implementation for the change UTxO calculation which contained some unnecessary set restrictions which may have come from a wrong merge-conflict resolutions, or simply inattention. This is now fix and implemented according to the wallet specification.

[piotr-iohk]

👍