From c3536af2094a0fcbc7b01ec6d8d63a42ca28e083 Mon Sep 17 00:00:00 2001
From: scanner <scanner@hive.kubestellar.io>
Date: Sun, 18 Oct 2026 04:24:55 -0400
Subject: [PATCH] fix: make Iterator polyfill cover jsdom vm contexts and
 spawned child processes
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The polyfill from #7443 fixed the worker-global Iterator but left two
failure modes that the prow presubmit (which never ran on #7443's
scripts-only diff) exposed on the next PR (#7440):

1. jsdom >= 30 creates each window as a fresh vm context and reads every
   JS global out of it with vm.runInContext(name, window). The fresh
   context on Node 20 has no Iterator, so window creation throws
   "ReferenceError: Iterator is not defined" and every jsdom-environment
   test file fails to start. The polyfill now wraps vm.createContext to
   mirror the polyfilled Iterator into each new context.

2. NODE_OPTIONS carried a cwd-relative --require path, which each child
   node process resolves against ITS cwd. Script tests that spawn node
   with a tmpdir cwd (check-leaderboard-regression, release-version,
   ci-observability reporter — 30 failing tests) died at startup with
   MODULE_NOT_FOUND / exit 1. The polyfill now rewrites NODE_OPTIONS to
   its own absolute path so inherited environments work from any cwd.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Signed-off-by: scanner <scanner@hive.kubestellar.io>
---
 .../fixed-iterator-polyfill-followups.md      |  1 +
 scripts/node-iterator-polyfill.cjs            | 45 +++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 changelog.d/fixed-iterator-polyfill-followups.md

diff --git a/changelog.d/fixed-iterator-polyfill-followups.md b/changelog.d/fixed-iterator-polyfill-followups.md
new file mode 100644
index 0000000000..7d6ca38c0c
--- /dev/null
+++ b/changelog.d/fixed-iterator-polyfill-followups.md
@@ -0,0 +1 @@
+Fixed the Node 20 `Iterator` polyfill so vitest passes again on the prow image: the polyfill is now mirrored into the vm contexts jsdom 30 creates per window, and `NODE_OPTIONS` is rewritten to the polyfill's absolute path so child `node` processes spawned by script tests from tmpdir cwds no longer die with MODULE_NOT_FOUND.
diff --git a/scripts/node-iterator-polyfill.cjs b/scripts/node-iterator-polyfill.cjs
index 4c218ba25c..23f514b245 100644
--- a/scripts/node-iterator-polyfill.cjs
+++ b/scripts/node-iterator-polyfill.cjs
@@ -13,4 +13,49 @@
 // prototype methods; on Node >= 22 the native implementation is kept.
 if (typeof globalThis.Iterator === 'undefined') {
   require('core-js/actual/iterator')
+
+  // jsdom >= 30 also reads every JS global out of the fresh vm context it
+  // creates per window (lib/jsdom/browser/Window.js: vm.runInContext(name,
+  // window) for each host global it found, which now includes our polyfilled
+  // `Iterator`). A fresh context on Node 20 has no native Iterator, so window
+  // creation throws "ReferenceError: Iterator is not defined" from inside
+  // runInContext. Mirror the polyfilled Iterator into every new context.
+  const vm = require('vm')
+  const originalCreateContext = vm.createContext
+  vm.createContext = function (...args) {
+    const context = originalCreateContext.apply(this, args)
+    // createContext returns the contextified object (or the context's global
+    // object with DONT_CONTEXTIFY); property sets on it reflect as globals
+    // inside the context.
+    const globalObject =
+      context !== null && typeof context === 'object' ? context : args[0]
+    try {
+      if (
+        globalObject &&
+        vm.runInContext('typeof Iterator', globalObject) === 'undefined'
+      ) {
+        globalObject.Iterator = globalThis.Iterator
+      }
+    } catch {
+      // Non-contextified or frozen targets: leave untouched.
+    }
+    return context
+  }
+}
+
+// The `test` script preloads this file with a cwd-relative path
+// (`--require ./scripts/node-iterator-polyfill.cjs`). Node resolves that
+// against the cwd of EACH process, so a child `node` process a test spawns
+// with a tmpdir cwd dies at startup with MODULE_NOT_FOUND before running
+// anything. Rewrite NODE_OPTIONS to this file's absolute path so inherited
+// environments keep working from any cwd.
+const RELATIVE_SPEC = './scripts/node-iterator-polyfill.cjs'
+if (
+  process.env.NODE_OPTIONS &&
+  process.env.NODE_OPTIONS.includes(RELATIVE_SPEC) &&
+  !__filename.includes(' ')
+) {
+  process.env.NODE_OPTIONS = process.env.NODE_OPTIONS
+    .split(RELATIVE_SPEC)
+    .join(__filename)
 }