Simplify API

At this stage, if waku relay is mounted then we always want to subscribe
to default topic.

We can re-introduce the flexibility once we know what matters to the user.

Resolves #17.

src/chat/index.ts

@@ -48,11 +48,6 @@ const ChatContentTopic = 'dingpu';
     await waku.dial(opts.staticNode);
   }
 
-  // TODO: Automatically subscribe, tracked with
-  // https://github.com/status-im/js-waku/issues/17
-  await waku.relay.subscribe();
-  console.log('Subscribed to waku relay');
-
   // If we connect to a peer with WakuStore, we run the protocol
   // TODO: Instead of doing it `once` it should always be done but
   // only new messages should be printed

src/lib/waku_relay/index.spec.ts

@@ -27,9 +27,6 @@ describe('Waku Relay', () => {
 
     await waku1.dialWithMultiAddr(waku2.libp2p.peerId, waku2.libp2p.multiaddrs);
 
-    await waku1.relay.subscribe();
-    await waku2.relay.subscribe();
-
     await Promise.all([
       new Promise((resolve) =>
         waku1.libp2p.pubsub.once('pubsub:subscription-change', () =>
@@ -95,7 +92,6 @@ describe('Waku Relay', () => {
         nimWaku = new NimWaku(makeLogFileName(this));
         await nimWaku.start({ staticnode: multiAddrWithId });
 
-        await waku.relay.subscribe();
         await new Promise((resolve) =>
           waku.libp2p.pubsub.once('gossipsub:heartbeat', resolve)
         );
@@ -165,8 +161,6 @@ describe('Waku Relay', () => {
         nimWaku = new NimWaku(this.test?.ctx?.currentTest?.title + '');
         await nimWaku.start();
 
-        await waku.relay.subscribe();
-
         await waku.dial(await nimWaku.getMultiaddrWithId());
 
         // Wait for identify protocol to finish
@@ -253,8 +247,6 @@ describe('Waku Relay', () => {
           waku2.dial(nimWakuMultiaddr),
         ]);
 
-        await Promise.all([waku1.relay.subscribe(), waku2.relay.subscribe()]);
-
         await Promise.all([
           new Promise((resolve) =>
             waku1.libp2p.pubsub.once('gossipsub:heartbeat', resolve)

src/lib/waku_relay/index.ts

@@ -294,11 +294,8 @@ export class WakuRelayPubsub extends Gossipsub {
 
 // This class provides an interface to execute the waku relay protocol
 export class WakuRelay {
-  constructor(private pubsub: Pubsub) {}
-
-  // At this stage we are always using the same topic so we do not pass it as a parameter
-  async subscribe() {
-    await this.pubsub.subscribe(constants.RelayDefaultTopic);
+  constructor(private pubsub: Pubsub) {
+    this.pubsub.subscribe(constants.RelayDefaultTopic);
   }
 
   async publish(message: WakuMessage) {