1 files changed, 45 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Iterator/prototype/flatMap/underlying-iterator-advanced-in-parallel.js b/js/src/tests/test262/built-ins/Iterator/prototype/flatMap/underlying-iterator-advanced-in-parallel.js
new file mode 100644
index 0000000000..cc5b401319
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Iterator/prototype/flatMap/underlying-iterator-advanced-in-parallel.js
@@ -0,0 +1,45 @@
+// |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: >
+  Underlying iterator is advanced after calling flatMap
+info: |
+  %Iterator.prototype%.flatMap ( mapper )
+
+features: [iterator-helpers]
+flags: []
+---*/
+let iterator = (function* () {
+  for (let i = 0; i < 5; ++i) {
+    yield i;
+  }
+})();
+
+let mapped = iterator.flatMap(x => [x]);
+
+let { value, done } = iterator.next();
+
+assert.sameValue(value, 0);
+assert.sameValue(done, false);
+
+iterator.next();
+iterator.next();
+
+({ value, done } = mapped.next());
+
+assert.sameValue(value, 3);
+assert.sameValue(done, false);
+
+({ value, done } = mapped.next());
+
+assert.sameValue(value, 4);
+assert.sameValue(done, false);
+
+({ value, done } = mapped.next());
+
+assert.sameValue(value, undefined);
+assert.sameValue(done, true);
+
+reportCompare(0, 0);