bug: Stopped filter node can receive messages

[AlejandroCabeza]

Problem

A filter node can still receive messages after stop has been called.
Also, this is unconsistent with relay's behaviour, which doesn't behave the same way.

Impact

TBD

To reproduce

1. Create two filter nodes, one will act as node and the other as server.
2. Subscribe both to the same pubsub and content topics.
3. Connect them.
4. Stop the client node.
5. Make the service node receive a message.
6. Client node will still receive the message.

There's a test named "Filter Client can receive messages after subscribing and stopping without unsubscribing" in waku_filter_v2/test_waku_client.nim that reproduces this behaviour (the ability to receive messages while stopped).

You can also check the test case named "Relay can receive messages after subscribing and stopping without unsubscribing" in waku_relay/test_protocol.nim, that reproduces the same behaviour (but crashes, hence it's ignored), mimicking the filter behaviour.

Remember to rename tests from xasyncTest to asyncTest to unignore them.

Expected behavior

Unclear, not RFC dependent.
Naming suggests it shouldn't work, but it does.

nwaku version/commit hash

• Wakunode: v0.20.0-rc.0-90-ga6d31c
• Git: 5551160
• PR Mention on Relay test case: test(waku-relay): Relay #2101 (comment)

[AlejandroCabeza]

According to this Discord Thread, this is intended behaviour.