pubsub/tasks/009-websocket-server-tests.md

id, name, status, depends_on, scope, risk, impact, level

id	name	status	depends_on	scope	risk	impact	level
websocket-server-tests	Write tests for WebSocket server event target adapter	completed	websocket-server-adapter websocket-client-tests	moderate	medium	component	implementation

Description

Write tests for createWebSocketServerEventTarget. This requires mocking multiple WebSocket connections and simulating the fan-out behavior.

Test scenarios from the architecture doc:

1. Topic-based fan-out — dispatchEvent sends only to connections subscribed to that event type
2. Subscription protocol — __subscribe/__unsubscribe control events correctly update the subscription map
3. Incoming aggregation — messages from any spoke dispatch to local listeners
4. Connection add/remove — new connections are tracked, disconnections clean up all subscriptions
5. Backpressure disconnect — slow consumers exceeding threshold are disconnected
6. Backpressure callback — onBackpressure is called before disconnecting
7. Direct messaging — events dispatched to "direct:${spokeId}" reach only the target spoke
8. Mixed topology — server adapter and client adapters can communicate bidirectionally

Acceptance Criteria

• test/event-target-websocket-server.test.ts exists and passes
• Mock strategy for multiple WebSocket connections established
• Test: addConnection/removeConnection track connections correctly
• Test: __subscribe control event adds connection to topic's subscriber set
• Test: __unsubscribe control event removes connection from topic's subscriber set
• Test: dispatchEvent sends only to connections subscribed to that topic
• Test: connections NOT subscribed to a topic do NOT receive events for that topic
• Test: malformed JSON from spokes is silently ignored
• Test: invalid __subscribe with empty/malformed topic is ignored
• Test: backpressure threshold disconnect — connections exceeding maxBufferedAmount are closed with code 1013
• Test: onBackpressure callback fires before disconnect
• Test: onConnection callback receives spoke target and WebSocket
• Test: onDisconnection callback fires on connection close
• Test: dispatchEvent always returns true
• Test: send failure (ws.send throws) removes connection and fires onDisconnection

References

• docs/architecture/event-targets/websocket-server.md (Test Plan section)
• src/event-target-websocket-server.ts

Notes

Completed as part of the websocket-server-adapter task. 46 test cases covering all acceptance criteria.

Summary

Tests were written alongside the adapter implementation. 46 tests pass, covering:

• Connection lifecycle (addConnection, removeConnection, automatic cleanup on close)
• Subscription protocol (__subscribe, __unsubscribe, idempotency, invalid topics)
• Topic-based fan-out (subscribed connections receive events, unsubscribed don't)
• Local listeners (addEventListener, removeEventListener, aggregation from spokes)
• Per-connection spoke targets (spoke.addEventListener, spoke.dispatchEvent)
• Error handling (malformed JSON, send failures, backpressure)
• Callbacks (onConnection, onDisconnection, onBackpressure)