1 files changed, 60 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Iterator/prototype/flatMap/iterable-to-iterator-fallback.js b/js/src/tests/test262/built-ins/Iterator/prototype/flatMap/iterable-to-iterator-fallback.js
new file mode 100644
index 0000000000..34d870c82f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Iterator/prototype/flatMap/iterable-to-iterator-fallback.js
@@ -0,0 +1,60 @@
+// |reftest| shell-option(--enable-iterator-helpers) skip-if(!this.hasOwnProperty('Iterator')||!xulRuntime.shell) -- iterator-helpers is not enabled unconditionally, requires shell-options
+// Copyright (C) 2023 Michael Ficarra. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-iteratorprototype.flatMap
+description: >
+  Iterator.prototype.flatMap falls back to treating mapper return values as iterators if the Symbol.iterator property is null/undefined
+info: |
+  %Iterator.prototype%.flatMap ( mapper )
+
+  5.b.vi. Let innerIterator be Completion(GetIteratorFlattenable(mapped)).
+
+includes: [compareArray.js]
+features: [iterator-helpers]
+flags: []
+---*/
+
+function* g() {
+  yield 0;
+}
+
+function* h() {
+  yield 0;
+  yield 1;
+  yield 2;
+}
+
+let iter = g().flatMap(v => {
+  let n = h();
+  return {
+    [Symbol.iterator]: 0,
+    next: () => n.next(),
+  };
+});
+
+assert.throws(TypeError, function () {
+  iter.next();
+});
+
+iter = g().flatMap(v => {
+  let n = h();
+  return {
+    [Symbol.iterator]: null,
+    next: () => n.next(),
+  };
+});
+
+assert.compareArray(Array.from(iter), [0, 1, 2]);
+
+iter = g().flatMap(v => {
+  let n = h();
+  return {
+    [Symbol.iterator]: undefined,
+    next: () => n.next(),
+  };
+});
+
+assert.compareArray(Array.from(iter), [0, 1, 2]);
+
+reportCompare(0, 0);