util: add createClassWrapper to internal/util

Utility function for wrapping an ES6 class with a constructor
function that does not require the new keyword

PR-URL: https://github.com/nodejs/node/pull/11391
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/test/parallel/test-internal-util-classwrapper.js b/test/parallel/test-internal-util-classwrapper.js
new file mode 100644
index 0000000000..52b3c2b0a9
--- /dev/null
+++ b/test/parallel/test-internal-util-classwrapper.js
@@ -0,0 +1,31 @@
+// Flags: --expose-internals
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const util = require('internal/util');
+
+const createClassWrapper = util.createClassWrapper;
+
+class A {
+  constructor(a, b, c) {
+    this.a = a;
+    this.b = b;
+    this.c = c;
+  }
+}
+
+const B = createClassWrapper(A);
+
+assert.strictEqual(typeof B, 'function');
+assert(B(1, 2, 3) instanceof B);
+assert(B(1, 2, 3) instanceof A);
+assert(new B(1, 2, 3) instanceof B);
+assert(new B(1, 2, 3) instanceof A);
+assert.strictEqual(B.name, A.name);
+assert.strictEqual(B.length, A.length);
+
+const b = new B(1, 2, 3);
+assert.strictEqual(b.a, 1);
+assert.strictEqual(b.b, 2);
+assert.strictEqual(b.c, 3);