1 files changed, 62 insertions, 0 deletions
diff --git a/js/src/tests/non262/Iterator/prototype/lazy-methods-interleaved.js b/js/src/tests/non262/Iterator/prototype/lazy-methods-interleaved.js
new file mode 100644
index 0000000000..0edc3cd467
--- /dev/null
+++ b/js/src/tests/non262/Iterator/prototype/lazy-methods-interleaved.js
@@ -0,0 +1,62 @@
+// |reftest| skip-if(!this.hasOwnProperty('Iterator'))
+
+//
+//
+/*---
+esid: pending
+description: Lazy %Iterator.prototype% method calls can be interleaved.
+info: >
+  Iterator Helpers proposal 2.1.5
+features: [iterator-helpers]
+---*/
+
+class TestIterator extends Iterator {
+  value = 0;
+  next() { 
+    return {done: false, value: this.value++};
+  }
+}
+
+function unwrapResult(result) {
+  // Unwrap the asIndexedPair return values.
+  while (Array.isArray(result.value)) {
+    result.value = result.value[1];
+  }
+  return result;
+}
+
+const methods = [
+  iter => iter.map(x => x),
+  iter => iter.filter(x => true),
+  iter => iter.take(2),
+  iter => iter.drop(0),
+  iter => iter.asIndexedPairs(),
+  iter => iter.flatMap(x => [x]),
+];
+
+for (const firstMethod of methods) {
+  for (const secondMethod of methods) {
+    const iterator = new TestIterator();
+    const firstHelper = firstMethod(iterator);
+    const secondHelper = secondMethod(iterator);
+
+    let firstResult = unwrapResult(firstHelper.next());
+    assertEq(firstResult.done, false);
+    assertEq(firstResult.value, 0);
+
+    let secondResult = unwrapResult(secondHelper.next());
+    assertEq(secondResult.done, false);
+    assertEq(secondResult.value, 1);
+
+    firstResult = unwrapResult(firstHelper.next());
+    assertEq(firstResult.done, false);
+    assertEq(firstResult.value, 2);
+
+    secondResult = unwrapResult(secondHelper.next());
+    assertEq(secondResult.done, false);
+    assertEq(secondResult.value, 3);
+  }
+}
+
+if (typeof reportCompare == 'function')
+  reportCompare(0, 0);