test: fix EPIPE on Windows

test-cluster-shared-leak.js was flaky because a worker can emit EPIPE.
Wait for workers to be listening so that EPIPE does not happen.

Fixes: #3956
PR-URL: #4173

Author: Trott

test/parallel/parallel.status

@@ -9,7 +9,6 @@ prefix parallel
 [$system==win32]
 test-child-process-fork-regr-gh-2847 : PASS,FLAKY
 test-cluster-net-send                : PASS,FLAKY
-test-cluster-shared-leak             : PASS,FLAKY
 test-tls-ticket-cluster              : PASS,FLAKY
 
 [$system==linux]

test/parallel/test-cluster-shared-leak.js

@@ -15,14 +15,18 @@ if (cluster.isMaster) {
   worker1 = cluster.fork();
   worker1.on('message', common.mustCall(function() {
     worker2 = cluster.fork();
-    conn = net.connect(common.PORT, common.mustCall(function() {
-      worker1.send('die');
-      worker2.send('die');
-    }));
-    conn.on('error', function(e) {
-      // ECONNRESET is OK
-      if (e.code !== 'ECONNRESET')
+    // make sure worker2 is listening before doing anything else
+    cluster.once('listening', function() {
+      conn = net.connect(common.PORT, common.mustCall(function() {
+        worker1.send('die');
+        worker2.send('die');
+      }));
+      conn.on('error', function(e) {
+        // ECONNRESET is OK
+        if (e.code === 'ECONNRESET')
+          return;
         throw e;
+      });
     });
   }));