Xconfess/Xconfess

[Wave 6] Add boundary and overflow tests for tipping contract fee arithmetic

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#1,665 opened on Jul 28, 2026

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contracthelp wantedsecuritytest

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Description

Problem

The tipping contract's fee and amount arithmetic hasn't been stress-tested for i128 edge cases: minimum tip amounts, fee rounding direction, and overflow near i128::MAX. A rounding bug here is a direct fund-handling bug.

Tasks

  • Add property-based tests (via proptest or manual boundary tests) for tip amount + fee calculation
  • Explicitly test: tip amount of 1 stroop, fee rounding when the result isn't evenly divisible, amounts near i128::MAX, zero-amount rejection
  • Document the rounding policy (round down vs round up on fees) in a doc comment on the calculation function
  • Add a regression test for any bug found

Acceptance Criteria

  • cargo test --workspace includes new boundary/property tests for tip fee math
  • Rounding policy is documented inline and matches actual contract behavior
  • No panics or silent overflow on any tested boundary value

Labels

contract, security, test, help wanted, Stellar Wave

Contributor guide

Research direction
Locate the tip fee calculation function in the Stellar contract, review its arithmetic and rounding behavior, then add boundary and property based tests using proptest for edge cases such as minimum tip amounts, rounding, and overflow near i128::MAX.
Tech stack
rust
Domain
blockchaintestingsecurity
Issue type
Test
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75