test: dynamic port in cluster worker dgram

Remove common.PORT from test-cluster-dgram-1 and
test-cluster-dgram-2, in order to eliminate the
possibility of port collision.

PR-URL: https://github.com/nodejs/node/pull/12487
Ref: https://github.com/nodejs/node/issues/12376
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

test/parallel/test-cluster-dgram-1.js

@@ -28,7 +28,7 @@ function master() {
     cluster.fork();
 
   // Wait until all workers are listening.
-  cluster.on('listening', common.mustCall(() => {
+  cluster.on('listening', common.mustCall((worker, address) => {
     if (++listening < NUM_WORKERS)
       return;
 
@@ -39,7 +39,7 @@ function master() {
     doSend();
 
     function doSend() {
-      socket.send(buf, 0, buf.length, common.PORT, '127.0.0.1', afterSend);
+      socket.send(buf, 0, buf.length, address.port, address.address, afterSend);
     }
 
     function afterSend() {
@@ -90,5 +90,5 @@ function worker() {
     }
   }, PACKETS_PER_WORKER));
 
-  socket.bind(common.PORT);
+  socket.bind(0);
 }

test/parallel/test-cluster-dgram-2.js

@@ -5,6 +5,7 @@ const PACKETS_PER_WORKER = 10;
 
 const cluster = require('cluster');
 const dgram = require('dgram');
+const assert = require('assert');
 
 
 if (common.isWindows) {
@@ -24,7 +25,14 @@ function master() {
 
   // Start listening on a socket.
   const socket = dgram.createSocket('udp4');
-  socket.bind(common.PORT);
+  socket.bind({ port: 0 }, common.mustCall(() => {
+
+    // Fork workers.
+    for (let i = 0; i < NUM_WORKERS; i++) {
+      const worker = cluster.fork();
+      worker.send({ port: socket.address().port });
+    }
+  }));
 
   // Disconnect workers when the expected number of messages have been
   // received.
@@ -40,10 +48,6 @@ function master() {
       cluster.disconnect();
     }
   }, NUM_WORKERS * PACKETS_PER_WORKER));
-
-  // Fork workers.
-  for (let i = 0; i < NUM_WORKERS; i++)
-    cluster.fork();
 }
 
 
@@ -57,13 +61,17 @@ function worker() {
   // send(), explicitly bind them to an ephemeral port.
   socket.bind(0);
 
+  process.on('message', common.mustCall((msg) => {
+    assert(msg.port);
+
     // There is no guarantee that a sent dgram packet will be received so keep
     // sending until disconnect.
     const interval = setInterval(() => {
-    socket.send(buf, 0, buf.length, common.PORT, '127.0.0.1');
+      socket.send(buf, 0, buf.length, msg.port, '127.0.0.1');
     }, 1);
 
     cluster.worker.on('disconnect', () => {
       clearInterval(interval);
     });
+  }));
 }