tests(pool): add SEP-41 interface compliance test suite

[K1NGD4VID]

Summary

Once balance/transfer/approve/allowance/transfer_from are implemented, they need a dedicated compliance test suite verifying they behave per the SEP-41 spec's edge cases (not just the repo's own happy paths already covered by unit tests for each function individually) — e.g. transferring more than balance, approving zero, allowance expiration by ledger number.

Acceptance Criteria

• New test module (contracts/pool/src/test.rs or a dedicated sep41_compliance test file) covering: transfer failure on insufficient balance, transfer_from failure once allowance is exhausted, allowance returning 0 past its expiration_ledger, approve overwriting a prior allowance rather than adding to it
• Test added/updated and passing (cargo test)

Tech Stack

Rust, Soroban SDK, contracts/pool/src/test.rs

[victoraitanke118-afk]

@victoraitanke118-afk has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hi Maintainer, I’ve reviewed the issue and have a clear understanding of what needs to be done. I’m confident I can work on it successfully. I’d appreciate it if you could consider assigning the issue to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @victoraitanke118-afk to this issue.

[Cyb3rflex]

@Cyb3rflex has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

I’d like to work on this issue because it focuses on validating a token interface against its expected specification, especially around security-sensitive edge cases. My background in cybersecurity and software development makes testing failure conditions and state transitions particularly relevant to me.
I would first review the existing pool contract implementation and its current unit tests, then map the relevant behavior against the SEP-41 requirements. I’d add a dedicated compliance test suite covering insufficient-balance transfers, exhausted allowances, allowance expiration by ledger number, and approval overwriting an existing allowance.
I would make the tests explicit about both the expected result and the resulting contract state, so they verify actual interface behavior rather than simply exercising the functions. I’d also follow the repository’s existing Soroban/Rust testing patterns and avoid modifying production contract logic unless the tests expose a genuine implementation issue.
Finally, I’d run cargo test and verify that the complete compliance suite passes alongside the existing tests.
kindly assign.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Cyb3rflex to this issue.

[Kaybee973]

@Kaybee973 has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

I’m interested in working on this issue and have experience fixing similar problems. I’d be happy to contribute.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Kaybee973 to this issue.

[drips-wave]

Congratulations, @Kaybee973! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on September 30, 2026.

🧑‍💻 @Kaybee973: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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