test: increase dgram ref()/unref() coverage

This commit completes code coverage for dgram's Socket#ref() and
Socket#unref() methods.

PR-URL: https://github.com/nodejs/node/pull/11240
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/test/parallel/test-dgram-unref.js b/test/parallel/test-dgram-unref.js
index 3908335f24..6fcdf5d23e 100644
--- a/test/parallel/test-dgram-unref.js
+++ b/test/parallel/test-dgram-unref.js
@@ -2,8 +2,18 @@
 const common = require('../common');
 const dgram = require('dgram');
 
-const s = dgram.createSocket('udp4');
-s.bind();
-s.unref();
+{
+  // Test the case of unref()'ing a socket with a handle.
+  const s = dgram.createSocket('udp4');
+  s.bind();
+  s.unref();
+}
+
+{
+  // Test the case of unref()'ing a socket with no handle.
+  const s = dgram.createSocket('udp4');
+
+  s.close(common.mustCall(() => s.unref()));
+}
 
 setTimeout(common.mustNotCall(), 1000).unref();