Return TransactionUnbalanced error for empty swap inputs/outputs #1381

Merged

crodas merged 1 commit from fix/error-message-empty-proofs into main

2025-12-03 09:49:42 +00:00

crodas commented

2025-12-03 01:08:17 +00:00

(Migrated from github.com)

Description

Fixes #1365 and probably #1356

When a swap request has empty inputs or empty outputs, the mint now correctly returns error code 11002 (TransactionUnbalanced) instead of 11010 (UnitMismatch).

The issue occurred because when inputs or outputs are empty, the unit verification returns None, and comparing Some(unit) != None would trigger a UnitMismatch error before the balance check could detect the actual problem.

Changes:

Add early validation in process_swap_request to catch empty inputs and return TransactionUnbalanced with proper amounts (0 input vs actual output amount)
Update verify_transaction_balanced to return TransactionUnbalanced when either input or output unit is None, instead of attempting unit comparison
Add test case documenting both scenarios:
- Swap with inputs but empty outputs (attempting to destroy tokens)
- Swap with empty inputs but outputs (attempting to create tokens)

This makes error handling more intuitive for API consumers, as the error code now correctly indicates the transaction is unbalanced (trying to create or destroy value) rather than suggesting a unit mismatch issue.

Notes to the reviewers

Suggested CHANGELOG Updates

CHANGED

ADDED

REMOVED

FIXED

Checklist

I followed the code style guidelines
I ran just final-check before committing

### Description Fixes #1365 and probably #1356 When a swap request has empty inputs or empty outputs, the mint now correctly returns error code 11002 (TransactionUnbalanced) instead of 11010 (UnitMismatch). The issue occurred because when inputs or outputs are empty, the unit verification returns `None`, and comparing `Some(unit) != None` would trigger a UnitMismatch error before the balance check could detect the actual problem. Changes: - Add early validation in process_swap_request to catch empty inputs and return TransactionUnbalanced with proper amounts (0 input vs actual output amount) - Update verify_transaction_balanced to return TransactionUnbalanced when either input or output unit is None, instead of attempting unit comparison - Add test case documenting both scenarios: - Swap with inputs but empty outputs (attempting to destroy tokens) - Swap with empty inputs but outputs (attempting to create tokens) This makes error handling more intuitive for API consumers, as the error code now correctly indicates the transaction is unbalanced (trying to create or destroy value) rather than suggesting a unit mismatch issue. ----- ### Notes to the reviewers  ----- ### Suggested [CHANGELOG](https://github.com/cashubtc/cdk/blob/main/CHANGELOG.md) Updates  #### CHANGED #### ADDED #### REMOVED #### FIXED ---- ### Checklist * [ ] I followed the [code style guidelines](https://github.com/cashubtc/cdk/blob/main/CODE_STYLE.md) * [ ] I ran `just final-check` before committing

thesimplekid (Migrated from github.com) reviewed

2025-12-03 01:08:17 +00:00

cdk-bot commented

2025-12-03 09:49:55 +00:00

(Migrated from github.com)

Successfully created backport PR for v0.14.x:

#1382

Successfully created backport PR for `v0.14.x`: - #1382

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