[FEATURE] Add cross-contract integration test suite

[Josue19-08]

🔖 Feature Title

Add cross-contract integration tests covering the full BNPL lifecycle

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📄 Description

Each contract has its own unit tests but there are no tests that exercise the contracts together. The `tests.rs` files in CreditLine have several TODOs for wiring up mock contracts that remain unimplemented. Integration tests are essential to verify that the CreditLine → Reputation → LiquidityPool → MerchantRegistry call chain works correctly as a system.

Current TODOs in `creditline-contract/src/tests.rs`:

• `// TODO: wire up MockMerchantRegistry/MockLiquidityPool`
• `// TODO: assert reputation score increased for user`
• `// TODO: assert liquidity pool received the repayment`

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✅ Tasks to complete

• Create a `tests/integration/` directory at the workspace root (or within each contract)
• Implement integration test: Full BNPL lifecycle
  1. Deploy all 4 contracts in the test environment
  2. Register a merchant in MerchantRegistry
  3. Set user reputation score ≥ 40 in Reputation contract
  4. Fund LiquidityPool with test tokens
  5. Create a loan via CreditLine → assert loan created, liquidity pool debited, merchant funded
  6. Repay the loan → assert loan completed, liquidity pool repaid with interest, reputation increased
• Implement integration test: Loan default path
  • Create loan → mark as defaulted → assert reputation decreased → assert guarantee received by pool
• Implement integration test: Unauthorized access rejection
  • Non-updater calling Reputation `set_score()` should panic
  • Non-CreditLine address calling LiquidityPool `fund_loan()` should panic
• Mock the SAC (Stellar Asset Contract) token for test environments
• Add integration test CI job in `.github/workflows/contracts-ci.yml`

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🗒️ Additional notes

• Depends on SC-09 and SC-11 being completed
• Use Soroban SDK's `testutils` feature: `env.register_contract()` to deploy contracts in-memory
• Each contract's address needs to be passed to the others during initialization
• The Reputation contract must have CreditLine registered as an updater via `set_updater()` before tests

[ekwe7]

I would love to work on this issue. I have experience building production ready applications and collaborating through GitHub workflows. I'll carefully analyze the current implementation, propose a reliable solution, and submit a well-tested PR. My focus is on clean code, maintainability, and timely delivery

[Menjay7]

Hi! I came across this issue and would love to work on it. I have experience with similar tasks and I'm confident I can investigate, implement a clean solution, and thoroughly test it before submitting a PR. If the issue is still open, I would appreciate it if you could assign it to me. Thank you!

[Mystery-CLI]

I have read through the required implementations and understand what to do can i work on it?

[Mystery-CLI]

I have read through the required implementations and understand what to do can i work on it?

[iam-mercy]

@iam-mercy has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi, please can i work on this issue, thank you

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

[Josue19-08]

Scope expanded — absorbs remaining work from #67

creditline-contract/src/tests.rs already has 102 tests covering the core scenarios of #67 (partial repayment, full repayment, overpayment, reputation score updates). However, 3 TODOs remain that require cross-contract mock wiring — exactly what this issue covers:

• // TODO: wire up a MockLiquidityPool; after create_loan verify fund_loan was called
• // TODO: Verify MockLiquidityPool::receive_guarantee(200) was called
• // TODO: wire up a MockLiquidityPool that returns available=0

These 3 assertions must be completed as part of the cross-contract integration test suite in this issue. Issue #67 will be closed and tracked here.

[Benjtalkshow]

Hi @Josue19-08, I'd like to work on this. I've reviewed the repo, so here's my concrete plan:

Current state

• 6 crates under contracts/; the 3 open TODOs in creditline-contract/src/tests.rs (~L1766, L1800, L1812) all need real cross-contract wiring.
• CreditLine already makes the real calls to test: lp_client.fund_loan(...) (lib.rs:294) and lp_client.receive_guarantee(...) on default (lib.rs:492). Wiring points confirmed: Reputation::set_updater gates set_score, and LiquidityPool::fund_loan/receive_guarantee are the authorized entries.

Plan

1. Add a workspace-level tests/integration/ crate using env.register_contract() + testutils.
2. Mock the SAC token via env.register_stellar_asset_contract_v2() for real test-token balances.
3. Full BNPL lifecycle: deploy 4 contracts → register merchant → set_updater(creditline) → reputation ≥ 40 → fund pool → create_loan (assert pool debited, merchant funded) → repay (assert completed, pool repaid with interest, reputation up).
4. Default path: create → default → assert reputation down + pool received guarantee.
5. Unauthorized access: #[should_panic] for non-updater set_score() and non-CreditLine fund_loan().
6. Replace the 3 TODOs with real assertions.
7. Add an integration-test job to .github/workflows/contracts-ci.yml.

Aware this depends on SC-09/SC-11 (SC-11 landed in 7f4671e). Can have a draft PR up in a few days. Could you assign this to me? Thanks!