(Medium) SC-19 real five-contract E2E happy-path loan lifecycle

[EmeditWeb]

Summary

The creditline suite has two harnesses: TestCtx (mock reputation + mock pool) driving the bulk of the 148 tests, and RealIntegrationCtx (contracts/creditline-contract/src/tests.rs:2535) which wires the real reputation, vendor-registry, pool and parameters contracts. The real harness today only exercises the create_loan (auto-funded) happy path (test_end_to_end_happy_path_across_all_contracts, :2754) — the full request → approve → fund → repay → score-up lifecycle through request_loan (contracts/creditline-contract/src/lib.rs:133-177) and approve_loan (:679-752) across all-real contracts is not covered end-to-end. The Pending → Active transition, the second validation pass at approval (:705-710), and the pool funding that happens only at approval (:726-733) are asserted only against mocks (TestCtx, used by 109 tests). This workstream adds the missing all-real lifecycle so the request/approve path is proven against the actual contracts.

Why this matters: the property is the request/approve/fund/repay lifecycle is proven end-to-end against the real contracts, not mocks. Mock assertions (was_fund_loan_called) cannot catch a divergence between the real pool's accounting and what creditline expects; the request→approve path has no real-contract coverage at all today.

Labels

area: contracts type: testing priority: medium

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Workstream 1 — All-real request → approve → fund → repay → score-up lifecycle

Objective

Add a RealIntegrationCtx-based test that drives a loan through request_loan → approve_loan → repay_loan against the real reputation, registry, pool and parameters contracts, asserting balances, statuses and the reputation increase.

Problem

RealIntegrationCtx (contracts/creditline-contract/src/tests.rs:2535-2666) registers ReputationContract (:2565), VendorRegistryContract (:2570), LiquidityPoolContract (:2572) and ParametersContract (:2575), and its existing tests use create_loan (:2745,2789) — the auto-funded path. The request_loan/approve_loan split exists only in the mock TestCtx (create_default_request at :301, and approve tests), where the pool and reputation are mocks and was_fund_loan_called (:353-355) stands in for real accounting. The real approval-time re-validation (validate_vendor/validate_reputation/validate_liquidity, lib.rs:705-710) and pool funding (fund_loan_from_pool, :726-733) therefore have no all-real assertion. vouching's suite likewise has no all-real three-contract flow (contracts/vouching-contract/src/tests.rs uses MockReputationContract throughout).

Scope

• contracts/creditline-contract/src/tests.rs (edit — add the all-real request/approve/repay test)
• contracts/vouching-contract/src/tests.rs (edit — see con-test-03; a vouch→creditline eligibility flow lives there)

Implementation

1. In RealIntegrationCtx, add a helper request_and_approve that calls creditline.request_loan and then creditline.approve_loan(admin, loan_id), funding the pool and minting the borrower's guarantee as needed.
2. Add test_real_lifecycle_request_approve_fund_repay_across_all_contracts: fund the real pool, register an active vendor in the real registry, set_score on the real reputation, request a loan, assert Pending and the guarantee transfer (lib.rs:159-161), approve it, assert Active + funded_at and the real pool's locked_liquidity increased, repay in full, assert Paid, the guarantee refund, and the real reputation score increase (early vs on-time, :1176).
3. Assert the real pool received the correct principal/interest split via pool.get_pool_stats() / receive_repayment effects, replacing the mock's was_receive_repayment_called (:360-362).
4. Keep the existing mock tests where they assert pure creditline-internal logic; this workstream adds the real-contract counterpart, it does not delete the mocks (that is con-test-04/06).

Acceptance Criteria

• Given a real pool with liquidity, a registered vendor and a scored borrower, when request_loan then approve_loan are called, then the loan is Active, the real pool locked_liquidity equals the pool contribution, and the guarantee sits with creditline.
• Given full repayment, when repay_loan is called, then the loan is Paid, the guarantee is refunded, and the real reputation score has increased by the configured reward.
• The test fails if the pool is not registered or the vendor is inactive at approval time (proving the real approval-time validation at :705-710 runs).

Testing

• Integration (the deliverable): the all-real lifecycle above.
• Regression: assert the Pending→Active transition leaves funded_at set (:717) — the mock path never checks the real pool side of this.

Shared acceptance criteria (whole epic)

• cargo fmt --all --check, cargo clippy --workspace --all-targets -- -D warnings, cargo build --locked --target wasm32-unknown-unknown --release, cargo test --locked all exit 0; test count does not drop.
• New tests live beside the existing real-integration tests and reuse RealIntegrationCtx; no production code changed.
• No secrets; no changes outside contracts/*-contract/src/tests.rs.

Security & compatibility considerations

• These are test-only changes; they must not weaken any assertion or introduce a mock where a real contract is required.
• The real registry must be initialized and the vendor approved for the flow to pass — mirrors production wiring; do not bypass with mock_all_auths shortcuts that hide auth failures beyond what the suite already uses.

References

• contracts/creditline-contract/src/tests.rs:2535-2666 — RealIntegrationCtx::setup + helpers.
• contracts/creditline-contract/src/tests.rs:2754-2793 — existing real happy path (create_loan).
• contracts/creditline-contract/src/tests.rs:159-205,301-330,350-376 — mock harness and was_* helpers to supersede.
• contracts/creditline-contract/src/lib.rs:133-177,679-752 — request_loan / approve_loan.
• contracts/vouching-contract/src/tests.rs — vouching suite (real-reputation flow is con-test-03).
• Extends the real-integration harness introduced for the existing test_end_to_end_* tests; adds the request/approve path they omit.

If you're solving this with AI

In scope: contracts/creditline-contract/src/tests.rs (and contracts/vouching-contract/src/tests.rs only as con-test-03 directs) — only.
Out of scope: any production lib.rs/storage.rs change; the other contracts' non-test code; new runtime deps; deleting existing mock tests (done in con-test-04/06); reformatting untouched tests.
Must: follow the repo PR template exactly; keep CI green for real (fmt + clippy + build + test); the new test must exercise real contracts (no mock externals); reference this issue (Closes #<n>); no secrets.

Contribution requirements: Follow the repo PR template exactly — https://github.com/StepFi-app/StepFi-Contracts/blob/main/.github/pull_request_template.md. Reference this issue in your PR. CI must pass green (fmt + clippy + build + tests). No secrets; no out-of-scope changes.

[shobhamerabacha-star]

Hello maintainers,

I would like to take on and implement this issue: (Medium) SC-19 real five-contract E2E happy-path loan lifecycle.

Technical Implementation Roadmap:

1. Formal Soroban Invariant Design: Audit storage layout (Instance, Persistent, Temporary) with strict TTL management and explicit require_auth guards.
2. Core Rust WASM Implementation: Implement deterministic state transition handlers eliminating arithmetic overflow risks using checked/saturating math.
3. Hermetic Testing Suite: Build comprehensive test cases in tests/ asserting authorized vs unauthorized invocations, mock auth environments, and edge value bounds.
4. Gas & Footprint Optimization: Profile CPU/memory instruction budgets under Soroban host environment to ensure optimal runtime efficiency.

Ready to implement and deliver a production-grade PR following all repository standards. Please feel free to assign!