fix: restore compatibility with binary parsers

Related: 5579d40

Author: darrachequesne

lib/index.ts

@@ -126,7 +126,7 @@ export class Adapter extends EventEmitter {
    */
   public broadcast(packet: any, opts: BroadcastOptions): void {
     const flags = opts.flags || {};
-    const packetOpts = {
+    const basePacketOpts = {
       preEncoded: true,
       volatile: flags.volatile,
       compress: flags.compress
@@ -135,15 +135,20 @@ export class Adapter extends EventEmitter {
     packet.nsp = this.nsp.name;
     const encodedPackets = this.encoder.encode(packet);
 
-    const firstPacketOpts = {
-      wsPreEncoded: "4" + encodedPackets[0], // "4" being the "message" packet type in Engine.IO
-      ...packetOpts
-    };
+    const packetOpts = encodedPackets.map(encodedPacket => {
+      if (typeof encodedPacket === "string") {
+        return {
+          ...basePacketOpts,
+          wsPreEncoded: "4" + encodedPacket // "4" being the "message" packet type in Engine.IO
+        };
+      } else {
+        return basePacketOpts;
+      }
+    });
 
     this.apply(opts, socket => {
-      socket.client.writeToEngine(encodedPackets[0], firstPacketOpts);
-      for (let i = 1; i < encodedPackets.length; i++) {
-        socket.client.writeToEngine(encodedPackets[i], packetOpts);
+      for (let i = 0; i < encodedPackets.length; i++) {
+        socket.client.writeToEngine(encodedPackets[i], packetOpts[i]);
       }
     });
   }

package-lock.json

@@ -66,7 +66,10 @@ describe("socket.io-adapter", () => {
         {
           id,
           client: {
-            writeToEngine() {
+            writeToEngine(payload, opts) {
+              expect(payload).to.eql("123");
+              expect(opts.preEncoded).to.eql(true);
+              expect(opts.wsPreEncoded).to.eql("4123");
               ids.push(id);
             }
           }
@@ -77,7 +80,7 @@ describe("socket.io-adapter", () => {
       server: {
         encoder: {
           encode() {
-            return [];
+            return ["123"];
           }
         }
       },
@@ -103,7 +106,10 @@ describe("socket.io-adapter", () => {
         {
           id,
           client: {
-            writeToEngine() {
+            writeToEngine(payload, opts) {
+              expect(payload).to.be.a(Buffer);
+              expect(opts.preEncoded).to.eql(true);
+              expect(opts.wsPreEncoded).to.be(undefined);
               ids.push(id);
             }
           }
@@ -114,7 +120,7 @@ describe("socket.io-adapter", () => {
       server: {
         encoder: {
           encode() {
-            return [];
+            return [Buffer.from([1, 2, 3])];
           }
         }
       },