---
id: redis-adapter-tests
name: Write tests for Redis event target adapter
status: completed
depends_on: [core-pubsub-tests]
scope: moderate
risk: medium
impact: component
level: implementation
---

## Description

The Redis event target adapter (`event-target-redis.ts`) is implemented but has zero tests. The architecture doc lists 7 specific test scenarios. Tests need a running Redis instance or a mock. Since this is a dev dependency, we can use `ioredis-mock` or start a Redis container in CI. The test strategy needs to handle the Redis dependency.

The architecture specifies these test scenarios:
1. Publish path — dispatchEvent sends to Redis with correct channel and serialized envelope
2. Subscribe path — addEventListener subscribes to Redis, onMessage dispatches to local listeners
3. Unsubscribe — removeEventListener unsubscribes from Redis when no listeners remain for a topic
4. Topic scoping — type:id topics are correctly formed
5. Envelope serialization — full `{ type, id, payload }` round-trips through JSON
6. Multiple listeners — multiple listeners on same topic, single Redis subscribe
7. Error propagation — what happens on connection failure

Note: test 7 (error propagation) is partially blocked by the missing error handling in the current implementation (tracked in task `redis-channel-prefix-and-error-handling`). The test should exist but may need to be adjusted once error handling is added.

## Acceptance Criteria

- [x] `test/event-target-redis.test.ts` exists and passes
- [x] Test approach for Redis dependency is decided (mock, container, or ioredis-mock)
- [x] Test: dispatchEvent publishes correct channel and serialized envelope
- [x] Test: addEventListener subscribes to Redis and dispatches to local listeners
- [x] Test: removeEventListener unsubscribes from Redis when no listeners remain
- [x] Test: type:id topic scoping works correctly
- [x] Test: EventEnvelope round-trips through JSON serialization
- [x] Test: multiple listeners on same topic result in single Redis subscribe
- [x] Test: custom serializer option works

## References

- docs/architecture/event-targets/redis.md
- src/event-target-redis.ts

## Notes

Test approach: Manual Redis mock (no external dependencies). The `createMockRedis()` helper creates a lightweight mock that tracks `publish`/`subscribe`/`unsubscribe` calls and provides `simulateMessage()` to trigger the `message` event handler. This avoids needing `ioredis-mock` or a running Redis instance.

Test 7 (error propagation) is not included because the current implementation lacks error handling — tracked in `redis-channel-prefix-and-error-handling` task.

## Summary

Implemented comprehensive tests for the Redis event target adapter using a manual mock approach (no external dependencies needed).

- Created: `test/event-target-redis.test.ts` (17 tests across 7 describe blocks)
- Tests: 17, all passing
- Coverage: dispatchEvent/publish path, addEventListener/subscribe path, removeEventListener/unsubscribe path, topic scoping, envelope round-trip serialization, multiple listeners (single Redis subscribe), custom serializer, EventListenerObject support