chore(peer-exchange): use an event listener to gauge if the service is mounted (#2071)

* chore: use service mounted event listener

* chore: update event name

* chore: change event name to isStarted

* chore: address comments

packages/discovery/src/peer-exchange/waku_peer_exchange_discovery.ts

@@ -50,12 +50,16 @@ export interface Options {
   maxRetries?: number;
 }
 
+interface CustomDiscoveryEvent extends PeerDiscoveryEvents {
+  "waku:peer-exchange:started": CustomEvent<boolean>;
+}
+
 export const DEFAULT_PEER_EXCHANGE_TAG_NAME = Tags.PEER_EXCHANGE;
 const DEFAULT_PEER_EXCHANGE_TAG_VALUE = 50;
 const DEFAULT_PEER_EXCHANGE_TAG_TTL = 100_000_000;
 
 export class PeerExchangeDiscovery
-  extends TypedEventEmitter<PeerDiscoveryEvents>
+  extends TypedEventEmitter<CustomDiscoveryEvent>
   implements PeerDiscovery
 {
   private readonly components: Libp2pComponents;
@@ -102,6 +106,10 @@ export class PeerExchangeDiscovery
       return;
     }
 
+    this.dispatchEvent(
+      new CustomEvent("waku:peer-exchange:started", { detail: true })
+    );
+
     log.info("Starting peer exchange node discovery, discovering peers");
 
     // might be better to use "peer:identify" or "peer:update"

packages/tests/tests/peer-exchange/compliance.spec.ts

@@ -24,16 +24,12 @@ describe("Peer Exchange", function () {
     beforeEachCustom(this, async () => {
       nwaku1 = new ServiceNode(makeLogFileName(this.ctx) + "1");
       nwaku2 = new ServiceNode(makeLogFileName(this.ctx) + "2");
-    });
 
-    tests({
-      async setup() {
       await nwaku1.start({
         relay: true,
         discv5Discovery: true,
         peerExchange: true
       });
-
       const enr = (await nwaku1.info()).enrUri;
 
       await nwaku2.start({
@@ -42,18 +38,27 @@ describe("Peer Exchange", function () {
         peerExchange: true,
         discv5BootstrapNode: enr
       });
+    });
 
+    tests({
+      async setup() {
         waku = await createLightNode();
         await waku.start();
 
         const nwaku2Ma = await nwaku2.getMultiaddrWithId();
 
-        // we do this because we want peer-exchange discovery to get initialised before we dial the peer which contains info about the other peer
-        setTimeout(() => {
-          void waku.libp2p.dialProtocol(nwaku2Ma, PeerExchangeCodec);
-        }, 1000);
+        const peerExchange = new PeerExchangeDiscovery(
+          waku.libp2p.components,
+          pubsubTopic
+        );
 
-        return new PeerExchangeDiscovery(waku.libp2p.components, pubsubTopic);
+        peerExchange.addEventListener("waku:peer-exchange:started", (event) => {
+          if (event.detail === true) {
+            void waku.libp2p.dialProtocol(nwaku2Ma, PeerExchangeCodec);
+          }
+        });
+
+        return peerExchange;
       },
       teardown: async () => {
         this.timeout(15000);