pubsub/tasks/001-core-pubsub-tests.md

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

id	name	status	depends_on	scope	risk	impact	level
core-pubsub-tests	Write tests for createPubSub, EventEnvelope, and in-process event target	completed		moderate	low	component	implementation

Description

The core createPubSub factory, EventEnvelope type, and the in-process (default EventTarget) path have no tests. These are the foundation of the entire package — every adapter builds on createPubSub. Write comprehensive tests that verify the core contract.

The architecture specifies these behaviors:

• createPubSub() with no config uses new EventTarget() (in-process)
• createPubSub({ eventTarget }) uses a custom event target
• publish(type, id, payload) dispatches a CustomEvent with type "type:id" and detail as EventEnvelope
• subscribe(type, id) returns a Repeater<EventEnvelope> (async iterable)
• publish throws on event types starting with __ (reserved for adapter control)
• Topic scoping uses the type:id convention
• subscribe cleanup: breaking out of the for await loop removes the listener

Acceptance Criteria

• test/create_pubsub.test.ts exists and passes
• Test: publish dispatches event with correct type:id topic
• Test: publish throws on __-prefixed event types
• Test: subscribe returns async iterable that yields EventEnvelope objects
• Test: subscribe envelope has correct type, id, payload fields
• Test: subscriber receives events only for the subscribed topic (type:id matching)
• Test: multiple subscribers on the same topic all receive events
• Test: subscriber cleanup — breaking out of for await loop removes the listener
• Test: createPubSub with custom eventTarget dispatches to that target
• Test: createPubSub without eventTarget uses new EventTarget() (in-process)

References

• docs/architecture/api-surface.md
• src/create_pubsub.ts
• src/types.ts

Notes

Used subscribe-based testing approach since createPubSub doesn't expose the internal target. Custom eventTarget tests use vi.spyOn on the provided target's dispatchEvent method.

Summary

Implemented comprehensive tests for createPubSub, EventEnvelope, and in-process event target.

• Created: test/create_pubsub.test.ts
• Tests: 11, all passing
• Coverage: publish dispatches correct type:id topic, publish throws on __-prefixed types, subscribe yields EventEnvelope objects, envelope has correct type/id/payload, topic scoping (type:id matching), multiple subscribers receive events, subscriber cleanup on break, custom eventTarget dispatches to provided target, default in-process EventTarget works