test: fix test-heapdump-zlib

PR-URL: #34499
Refs: #34048
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>

test/pummel/test-heapdump-zlib.js

@@ -1,17 +1,28 @@
 // Flags: --expose-internals
 'use strict';
-require('../common');
+const common = require('../common');
 const { validateSnapshotNodes } = require('../common/heap');
 const zlib = require('zlib');
 
 validateSnapshotNodes('Node / ZlibStream', []);
-// eslint-disable-next-line no-unused-vars
-const gunzip = zlib.createGunzip();
+
+const gzip = zlib.createGzip();
 validateSnapshotNodes('Node / ZlibStream', [
   {
     children: [
-      { node_name: 'Zlib', edge_name: 'wrapped' },
-      { node_name: 'Node / zlib_memory', edge_name: 'zlib_memory' }
+      { node_name: 'Zlib', edge_name: 'wrapped' }
+      // No entry for memory because zlib memory is initialized lazily.
     ]
   }
 ]);
+
+gzip.write('hello world', common.mustCall(() => {
+  validateSnapshotNodes('Node / ZlibStream', [
+    {
+      children: [
+        { node_name: 'Zlib', edge_name: 'wrapped' },
+        { node_name: 'Node / zlib_memory', edge_name: 'zlib_memory' }
+      ]
+    }
+  ]);
+}));