[SC-50] Property-based tests for multisig thresholds and share accounting

[yusuftomilola]

Overview

Existing tests are example-based. Multisig threshold logic and fractional share accounting are invariant-heavy — exactly where property testing finds the edge cases humans miss.

Tasks

• Add proptest as a dev-dependency for the relevant crates.
• Multisig invariant: for any generated sequence of signer additions, removals, and approvals, a proposal executes only when distinct current signers meeting the threshold have approved.
• Share accounting invariant: after any sequence of tokenize, transfer, and detokenize operations, the sum of all holder balances equals total supply and no balance is negative.
• Escrow invariant: value in equals value out plus value held — never created or destroyed.
• Constrain generators to realistic ranges and keep the case count CI-appropriate.
• Commit any counterexample found as a permanent regression test.

Acceptance Criteria

• Property tests exist for multisig thresholds, share conservation, and escrow balance.
• They run in CI within a reasonable time budget.
• Discovered counterexamples are fixed and pinned as regression tests.

Dependencies

Best after [SC-32] and [SC-40] establish baseline coverage.

Notes for Contributors

Requires Rust + Soroban. Workspace: contracts/ (soroban-sdk 22, members: assetsup, contrib, multisig-wallet, multisig_transfer, asset-maintenance). Run cargo test --all, cargo fmt --all -- --check, and cargo clippy --all-targets --all-features -- -D warnings before opening a PR — CI enforces all three. Comment below to be assigned.

[TomikeDS]

@TomikeDS has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

can i work on this issue?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @TomikeDS to this issue.

[drips-wave]

Congratulations, @TomikeDS! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

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