Feature: add shared test helpers plus invariant-style lifecycle tests

[yahia008]

Status: Open - unassigned
Labels: testing, quality
Priority: Medium

Description:
Both contracts repeat setup code, and the suite would benefit from more reusable fixtures plus a few invariant-style checks around fund conservation and terminal states.

Tasks:

• Extract common test helpers
• Add invariant-oriented tests for escrow balance conservation and terminal transitions

[gracepeterfejokwu]

@gracepeterfejokwu has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

hi maintainer i'll like to work on this issue

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

[stellajose]

@stellajose has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I will implement and fix this issue according to the design requirement and to fit your acceptance criteria

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

[drips-wave]

Congratulations, @stellajose! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @stellajose: 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.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊