fix: emit CampaignExpired event in expire_campaign

[kragent66-glitch]

Problem

expire_campaign emitted CampaignCancelled, misreporting an expired campaign as cancelled.

Approach

• Add CampaignExpired event struct in events.rs
• Emit it from expire_campaign (1-line change in lib.rs)
• Add test_expire_event regression test

Verification

Minimal scoped change following existing event patterns.

Closes #64

[JamesVictor-O]

The core fix is correct — expire_campaign was emitting CampaignCancelled instead of CampaignExpired, and swapping the event struct at the call site is the right change.

However, the added test in test.rs (test_expire_event::test_campaign_expired_event) does not compile:

error[E0433]: cannot find module or crate `hex` in this scope
   --> contracts/campaign-escrow/src/test.rs:1967:35
error[E0599]: no method named `abi_encode` found for struct `soroban_sdk::events::Events`
error[E0599]: no method named `iter` found for struct `ContractEvents`
error[E0599]: no function or associated item named `generate` found for struct `soroban_sdk::Address`

Specifically:

• hex::encode(...) — the hex crate isn't a dependency of this crate, and isn't needed here.
• env.events().abi_encode(...) — no such method exists on soroban_sdk::events::Events.
• env.events().all().iter() — ContractEvents (the type returned by .all()) needs a different access pattern; check how existing tests in this file assert on emitted events (e.g. search for other env.events() usage) and follow that pattern instead.
• Address::generate(&env) needs use soroban_sdk::testutils::Address as _; in scope (see how other test modules in this file import it).

Simplest fix: look at an existing test elsewhere in test.rs that already asserts an event was emitted (e.g. around SurplusReclaimed or DisputeFrozen) and mirror that pattern rather than hand-rolling XDR/hex encoding — the existing pattern is much simpler and will compile.

Please push a fix and I'll re-review. Ran cargo test --workspace locally to confirm the compile failure.

[JamesVictor-O]

Correction to my review above: I said to mirror an existing event-assertion test elsewhere in test.rs, but on checking, no existing test in this file actually asserts on emitted events — so there's no example to copy. Concrete guidance instead:

env.events().all() returns a soroban_sdk::testutils::ContractEvents (not a plain iterable), which exposes:

• .events() → &[xdr::ContractEvent] (raw XDR), or
• PartialEq<Vec<(Address, Vec<Val>, Val)>> — so you can assert equality directly against a vector of (contract_address, topics_vec, data_val) tuples without any hex/XDR encoding at all.

The simplest fix is likely:

assert_eq!(
    env.events().all(),
    vec![
        &env,
        (
            contract_id.clone(),
            (symbol_short!("...") /* whatever topic Campaign
Expired's #[topic] derives */,).into_val(&env),
            (id, refund).into_val(&env), // or however the event's data fields serialize
        ),
    ]
);

(check the #[contractevent] macro output / another Soroban project's tests for the exact topic symbol and data shape CampaignExpired derives — I don't have that mapping handy, but the ContractEvents: PartialEq<Vec<(Address, Vec<Val>, Val)>> impl is the supported comparison path in soroban-sdk 27, not manual XDR/hex encoding).

No hex crate, no abi_encode needed either way.

[kragent66-glitch]

Pushed a fix addressing the review — and found a deeper bug in the process.

What was wrong:

1. The previous commit changed the wrong call site — cancel_campaign was emitting CampaignExpired while expire_campaign (the subject of bug: expire_campaign reuses the CampaignCancelled event instead of a distinct CampaignExpired event #64) kept emitting CampaignCancelled. Both are now correct: cancel_campaign → CampaignCancelled, expire_campaign → CampaignExpired.
2. The regression test did not compile (no hex dep, no abi_encode/.iter() on the events API) and never actually called expire_campaign, so it could not have caught the swapped events even if it had compiled.

The rewritten test follows the supported soroban-sdk 27 path you outlined:

• env.events().all().filter_by_contract(&contract_id) to scope to this contract
• Event::to_xdr (the documented test-comparison helper) instead of hex/abi_encode
• Asserts refunded_amount equals the unallocated balance (budget − 2 × 1M committed), not 0

Verified locally: cargo fmt --check ✓, cargo clippy --workspace --all-targets -- -D warnings ✓, cargo test --workspace → 124 passed, 0 failed (88 escrow + 15 dispute + 21 pause). The new test fails against the pre-fix code (it caught campaign_cancelled vs campaign_expired), so it's a genuine regression guard.

[JamesVictor-O]

Automated review: confirmed the change is exactly what it claims — expire_campaign now emits CampaignExpired instead of CampaignCancelled, with cancel_campaign's own emit untouched (no duplicate/leftover). New event struct mirrors CampaignCancelled's shape and the file's existing event conventions. Regression test asserts the exact XDR-encoded event (topic + data), not just "doesn't panic". No fund-movement or state-transition logic touched. CI green. Approving.

[JamesVictor-O]

⚠️ Merge conflict — this PR was approved, but #72 (checks-effects-interactions reorder) merged first and now conflicts with this branch in exactly one spot.

contracts/campaign-escrow/src/lib.rs, in expire_campaign: #72 moved the token transfer to after storage::set_campaign while keeping the events::CampaignCancelled { ... } call; this PR renames that same call to events::CampaignExpired { ... } at its old position. events.rs and test.rs merge cleanly — only this one hunk conflicts.

Resolution: rebase on latest main, keep #72's write-then-transfer ordering, and just rename the event call within it to events::CampaignExpired { ... }. Since maintainerCanModify is off for this PR, I can't push the rebase myself — could you (or whoever picks this up) rebase and push? Happy to re-review and merge right after.