[peer discovery] Add test suite and add it to all implementations

[jacobheun]

Currently this repo has no test suite, it needs one. Once that's in place, all current implementations need to have the test suite added to them.

Tests

• Ensure implementations conform to the api, https://github.com/libp2p/interface-peer-discovery#api
• Ensure discovery services do not emit their own PeerInfo. Ref: Dont discover self js-libp2p#356
  • Note: The api will need to change to pass in libp2p when the service is initialized so that it has knowledge of its own PeerInfo instance.

Implementations

Add the test suite to:

• js-libp2p-mdns
• js-libp2p-bootstrap
• js-libp2p-kad-dht randomWalk
• js-libp2p-webrtc-star
• js-libp2p-websocket-star

[jacobheun]

Adding thoughts on tests here for when this is implemented. Feel free to comment with additional thoughts.

Tests

• should be able to find another peer

Modules will be responsible for creating the setup needed for discovery. .start() will be called on the module and it is expected that the peer will be discovered before the test times out. Implementing modules should take care to make the discovery happen quickly, to avoid lengthy tests. For example, an interval based discovery, like libp2p-bootstrap should trigger shortly after startup.

• should not emit events when stopped

Modules should emit peers infinitely. .start() will be called followed by .stop() with a small delay (100 ms?). Modules will be expected to have emitted discovery events after start and before stop. After stop, any emitted events will fail the test.

• ...

[jacobheun]

It might also be valuable to do a test to verify we are not emitting ourselves as a discovered peer.

[dirkmc]

Maybe also a test to ensure discovery continues after start, stop, start

[vasco-santos]

We already added these to each discovery implementation, except for the DHT. The DHT already has an issue to track it support once we refactor it