1 files changed, 51 insertions, 0 deletions
diff --git a/testing/web-platform/tests/js/builtins/weakrefs/reentrancy.optional.any.js b/testing/web-platform/tests/js/builtins/weakrefs/reentrancy.optional.any.js
new file mode 100644
index 0000000000..fa7b7d55c4
--- /dev/null
+++ b/testing/web-platform/tests/js/builtins/weakrefs/reentrancy.optional.any.js
@@ -0,0 +1,51 @@
+// META: script=/common/gc.js
+// META: script=resources/maybe-garbage-collect.js
+// ├──> maybeGarbageCollectAndCleanupAsync
+// └──> resolveGarbageCollection
+/*---
+esid: sec-properties-of-the-finalization-registry-constructor
+---*/
+
+let called = 0;
+let endOfCall = 0;
+let finalizationRegistry = new FinalizationRegistry(function() {});
+
+function callback(holding) {
+  called += 1;
+
+  if (called === 1) {
+    // Atempt to re-enter the callback.
+    let nestedCallbackRan = false;
+    finalizationRegistry.cleanupSome(() => { nestedCallbackRan = true });
+    assert_equals(nestedCallbackRan, true);
+  }
+
+  endOfCall += 1;
+}
+
+function emptyCells() {
+  let o1 = {};
+  let o2 = {};
+  // Register more than one objects to test reentrancy.
+  finalizationRegistry.register(o1, 'holdings 1');
+  finalizationRegistry.register(o2, 'holdings 2');
+
+  let prom = maybeGarbageCollectAndCleanupAsync(o1);
+  o1 = null;
+
+  return prom;
+}
+
+promise_test(() => {
+  return (async () => {
+    assert_implements(
+      typeof FinalizationRegistry.prototype.cleanupSome === 'function',
+      'FinalizationRegistry.prototype.cleanupSome is not implemented.'
+    );
+    await emptyCells();
+    finalizationRegistry.cleanupSome(callback);
+
+    assert_equals(called, 1, 'callback was called');
+    assert_equals(endOfCall, 1, 'callback finished');
+  })().catch(resolveGarbageCollection);
+}, 'cleanupCallback has only one optional chance to be called for a GC that cleans up a registered target.');