Add explicit regression test for the max_settlement_amount(asset, 0) disables-cap sentinel

[Jagadeeshftw]

📌 Description

set_max_settlement_amount(asset, amount) documents 0 as disabling the cap per the README's table, mirroring set_min_liquidity's 0-disables-floor convention. This "0 means disabled" sentinel is a common source of off-by-one bugs (e.g. accidentally treating 0 as "cap of zero, reject everything") and deserves an explicit named test rather than incidental coverage.

🧩 Requirements and context

• Add a test: with max_settlement_amount(asset) at 0, open a large settlement via open_settlement and assert it succeeds (cap is disabled, not zero).
• Add a companion test with a nonzero cap confirming a settlement exceeding it is correctly rejected.
• Cross-check set_min_liquidity's equivalent 0 sentinel has the same explicit test coverage; add it if missing.

🛠️ Suggested execution

• Add both tests to src/test.rs.
• Fix open_settlement's cap-check logic in src/lib.rs if the 0 sentinel is mishandled.

✅ Acceptance criteria

• 0 correctly disables the settlement-amount cap.
• A nonzero cap correctly rejects an over-cap settlement.
• Both scenarios covered by named regression tests, including the min_liquidity equivalent.

🔒 Security notes

An inverted sentinel here would either silently disable a risk control or brick settlements entirely for an asset — worth locking down explicitly.

📋 Guidelines

• Minimum 95% test coverage
• Clear documentation
• Timeframe: 96 hours

[GBOYEE]

Hey, I'd like to help with this (Add explicit regression test for the max_settlement_amount(asset, 0...). I'll write the missing test coverage and wire it in. Happy to submit a PR for this once the bot assigns it.

[grantfox-oss]

🦊 GrantFox — @mordabdul1 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #81)
2. Your PR will be reviewed by the AnchorNet-Org maintainers

Good luck! Track your progress on GrantFox.

[Jagadeeshftw]

@GBOYEE thanks for volunteering for the max_settlement_amount sentinel test — you're at capacity though (6 assigned, dozens more requested). get a PR or two landed on your current issues and we can revisit this one.

[Jagadeeshftw]

assigned via repo automation. go ahead and open a PR with 'Closes #81' in the description when ready. join the community if you haven't: t.me/+vTbe0hOUKrFhNTJl