[CT-17] Write integration tests for the full shipment and escrow lifecycle

[mftee]

Problem

The shipment and escrow contracts are each tested in isolation. There are no integration tests verifying that the full end-to-end flow — creating a shipment, funding escrow, accepting, going in-transit, delivering, and releasing funds — works correctly when both contracts interact.

Proposed Solution

Write integration tests inside contracts/package/tests/integration/ that deploy both contracts in the same Soroban test environment and exercise complete lifecycle flows.

Note: All work must be done inside the contracts/package/ directory. Do not modify any existing contract files outside this folder.

Acceptance Criteria

• Test flow 1 — Happy path: create shipment → fund escrow → accept → in-transit → deliver → release funds → verify carrier token balance increased
• Test flow 2 — Dispute path: create shipment → fund escrow → deliver → open dispute → admin resolves with refund → verify shipper token balance restored
• Test flow 3 — Cancellation path: create shipment → fund escrow → cancel → refund → verify shipper token balance restored
• Each test deploys fresh contract instances and a mock SEP-41 token
• All three flows run successfully via cargo test from within contracts/package/tests/integration/

[phertyameen]

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

I’d like to work on this issue. I have experience with Soroban smart contracts, testing, and secure contract design, and I can implement the required functionality with clean, maintainable code and comprehensive test coverage.

I’ll follow the project requirements closely, keep changes scoped to the specified files/directories, and ensure the solution is reliable and CI-friendly.

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

[drips-wave]

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

🧑‍💻 @phertyameen: 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 🌊