test_runner: fix lazy test.assert accessor

PR-URL: https://github.com/nodejs/node/pull/61097
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Pietro Marchini <pietro.marchini94@gmail.com>
Reviewed-By: Jacob Smith <jacob@frende.me>
Reviewed-By: Aviv Keller <me@aviv.sh>

lib/test.js

@@ -62,14 +62,18 @@ ObjectDefineProperty(module.exports, 'snapshot', {
   },
 });
 
+let lazyAssert;
+
 ObjectDefineProperty(module.exports, 'assert', {
   __proto__: null,
   configurable: true,
   enumerable: true,
   get() {
-    const { register } = require('internal/test_runner/assert');
-    const assert = { __proto__: null, register };
-    ObjectDefineProperty(module.exports, 'assert', assert);
-    return assert;
+    if (lazyAssert === undefined) {
+      const { register } = require('internal/test_runner/assert');
+      lazyAssert = { __proto__: null, register };
+    }
+
+    return lazyAssert;
   },
 });