Add regression test that extend_instance_ttl actually persists across a simulated ledger-time jump

[Jagadeeshftw]

📌 Description

extend_instance_ttl(env, caller) in src/lib.rs is callable by admin or operator and extends the contract instance/code TTL "so it survives long inactivity" per the README. There's an authorization test opportunity (non-admin/non-operator rejection) and a functional-correctness opportunity (TTL actually extends, verified by advancing simulated ledger time in the test environment) that should both be explicit, named tests rather than incidental coverage.

🧩 Requirements and context

• Add a test asserting a caller who is neither admin nor operator is rejected by extend_instance_ttl.
• Add a test that advances the test environment's ledger sequence/timestamp past what the instance would survive without extension, and confirms the contract remains callable after extend_instance_ttl was invoked.
• Use Soroban's test-environment ledger manipulation utilities already available via the soroban_sdk test harness.

🛠️ Suggested execution

• Add both tests to src/test.rs, using env.ledger().set(...) (or the SDK's equivalent) to simulate time passing.
• If the authorization check is missing or the TTL extension doesn't actually take effect, fix extend_instance_ttl in src/lib.rs.

✅ Acceptance criteria

• Non-admin/non-operator callers are rejected.
• TTL extension is proven to take effect via a simulated ledger-time jump.
• Both scenarios are covered by named regression tests.

🔒 Security notes

Confirms the admin/operator-only guard on a lifecycle-critical entrypoint, and that the extension is not a no-op that silently leaves the contract vulnerable to archival.

📋 Guidelines

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

[GBOYEE]

Hi team \u2014 I'd like to take this on (Add regression test that extend_instance_ttl actually persists acro...). I'll implement it to spec and add tests. Happy to coordinate if anyone's already looking at it.

[Jagadeeshftw]

@GBOYEE the extend_instance_ttl ledger-jump test sounds useful, but you're already at the 6-issue assignment cap and have interest posted on a large number of other issues too. once a few of those land as merged PRs there'll be room to pick this up.

[Jagadeeshftw]

@GBOYEE update on the cap: on review, #99/#98/#91 already had a PR referencing them (PR #102), so those freed up. i used the freed slots for your three oldest pending requests (#97, #95, #81), which puts you back at the 6-issue cap. this one (#72) will have to wait until you close out some of what's assigned. thanks for the patience.

[grantfox-oss]

🦊 GrantFox — @GBOYEE 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 #72)
2. Your PR will be reviewed by the AnchorNet-Org maintainers

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