1 files changed, 64 insertions, 0 deletions
diff --git a/js/src/tests/non262/AsyncIterator/prototype/lazy-methods-multiple-return-close-iterator-once.js b/js/src/tests/non262/AsyncIterator/prototype/lazy-methods-multiple-return-close-iterator-once.js
new file mode 100644
index 0000000000..4ccb6fd4b1
--- /dev/null
+++ b/js/src/tests/non262/AsyncIterator/prototype/lazy-methods-multiple-return-close-iterator-once.js
@@ -0,0 +1,64 @@
+// |reftest| skip-if(!this.hasOwnProperty('AsyncIterator'))
+
+//
+//
+/*---
+esid: pending
+description: Calling `.return()` on a lazy %AsyncIterator.prototype% method multiple times closes the source iterator once.
+info: >
+  Iterator Helpers proposal 2.1.6
+features: [iterator-helpers]
+---*/
+
+class TestIterator extends AsyncIterator {
+  async next() { 
+    return {done: false, value: 1};
+  }
+
+  closeCount = 0;
+  async return(value) {
+    this.closeCount++;
+    return {done: true, value};
+  }
+}
+
+async function* gen(x) { yield x; }
+
+const methods = [
+  iter => iter.map(x => x),
+  iter => iter.filter(x => x),
+  iter => iter.take(1),
+  iter => iter.drop(0),
+  iter => iter.asIndexedPairs(),
+  iter => iter.flatMap(gen),
+];
+
+(async () => {
+  // Call `return` after stepping the iterator once:
+  for (const method of methods) {
+    const iter = new TestIterator();
+    const iterHelper = method(iter);
+    
+    await iterHelper.next();
+    assertEq(iter.closeCount, 0);
+    await iterHelper.return();
+    assertEq(iter.closeCount, 1);
+    await iterHelper.return();
+    assertEq(iter.closeCount, 1);
+  }
+
+  // Call `return` before stepping the iterator:
+  for (const method of methods) {
+    const iter = new TestIterator();
+    const iterHelper = method(iter);
+
+    assertEq(iter.closeCount, 0);
+    await iterHelper.return();
+    assertEq(iter.closeCount, 1);
+    await iterHelper.return();
+    assertEq(iter.closeCount, 1);
+  }
+})();
+
+if (typeof reportCompare == 'function')
+  reportCompare(0, 0);