test: add tests for hasItems method in FreeList

PR-URL: #27588
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

test/parallel/test-freelist.js

@@ -28,3 +28,13 @@ assert.strictEqual(flist1.free({ id: 'test5' }), false);
 assert.strictEqual(flist1.alloc().id, 'test3');
 assert.strictEqual(flist1.alloc().id, 'test2');
 assert.strictEqual(flist1.alloc().id, 'test1');
+
+// Check list has elements
+const flist2 = new FreeList('flist2', 2, Object);
+assert.strictEqual(flist2.hasItems(), false);
+
+flist2.free({ id: 'test1' });
+assert.strictEqual(flist2.hasItems(), true);
+
+flist2.alloc();
+assert.strictEqual(flist2.hasItems(), false);