fix: dial protocol should throw if no protocol is provided (#914)

BREAKING CHANGE: dialProtocol does not return connection when no protocols are provided

src/errors.js

@@ -11,6 +11,7 @@ exports.codes = {
   PUBSUB_NOT_STARTED: 'ERR_PUBSUB_NOT_STARTED',
   DHT_NOT_STARTED: 'ERR_DHT_NOT_STARTED',
   CONN_ENCRYPTION_REQUIRED: 'ERR_CONN_ENCRYPTION_REQUIRED',
+  ERR_INVALID_PROTOCOLS_FOR_STREAM: 'ERR_INVALID_PROTOCOLS_FOR_STREAM',
   ERR_CONNECTION_ENDED: 'ERR_CONNECTION_ENDED',
   ERR_CONNECTION_FAILED: 'ERR_CONNECTION_FAILED',
   ERR_NODE_NOT_STARTED: 'ERR_NODE_NOT_STARTED',

src/index.js

@@ -462,26 +462,23 @@ class Libp2p extends EventEmitter {
   }
 
   /**
-   * Dials to the provided peer and handshakes with the given protocol.
+   * Dials to the provided peer and tries to handshake with the given protocols in order.
    * If successful, the known metadata of the peer will be added to the nodes `peerStore`,
-   * and the `Connection` will be returned
+   * and the `MuxedStream` will be returned together with the successful negotiated protocol.
    *
    * @async
    * @param {PeerId|Multiaddr|string} peer - The peer to dial
    * @param {string[]|string} protocols
    * @param {object} [options]
    * @param {AbortSignal} [options.signal]
-   * @returns {Promise<Connection|{ stream: MuxedStream; protocol: string; }>}
    */
   async dialProtocol (peer, protocols, options) {
-    const connection = await this._dial(peer, options)
+    if (!protocols || !protocols.length) {
-
+      throw errCode(new Error('no protocols were provided to open a stream'), codes.ERR_INVALID_PROTOCOLS_FOR_STREAM)
-    // If a protocol was provided, create a new stream
-    if (protocols && protocols.length) {
-      return connection.newStream(protocols)
     }
 
-    return connection
+    const connection = await this._dial(peer, options)
+    return connection.newStream(protocols)
   }
 
   /**

test/dialing/direct.node.js

@@ -352,6 +352,25 @@ describe('Dialing (direct, TCP)', () => {
       await pWaitFor(() => remoteConn.streams.length === 0)
     })
 
+    it('should throw when using dialProtocol with no protocols', async () => {
+      libp2p = new Libp2p({
+        peerId,
+        modules: {
+          transport: [Transport],
+          streamMuxer: [Muxer],
+          connEncryption: [Crypto]
+        }
+      })
+
+      await expect(libp2p.dialProtocol(remotePeerId))
+        .to.eventually.be.rejectedWith(Error)
+        .and.to.have.property('code', ErrorCodes.ERR_INVALID_PROTOCOLS_FOR_STREAM)
+
+      await expect(libp2p.dialProtocol(remotePeerId, []))
+        .to.eventually.be.rejectedWith(Error)
+        .and.to.have.property('code', ErrorCodes.ERR_INVALID_PROTOCOLS_FOR_STREAM)
+    })
+
     it('should be able to use hangup to close connections', async () => {
       libp2p = new Libp2p({
         peerId,