Add test case where IteratorStepValue throws

Author: G-Lee1031

test/language/destructuring/binding/iteratorstepvalue-throws.js

@@ -0,0 +1,35 @@
+// Copyright (C) 2026 Garham Lee. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-runtime-semantics-bindinginitialization
+description: >
+    IteratorStepValue throws when iteratorRecord.[[NextMethod]] is undefined.
+info: |
+    Runtime Semantics: BindingInitialization (_value_, _environment_)
+
+    BindingPattern : ArrayBindingPattern
+    1. Let _iteratorRecord_ be ? GetIterator(_value_, ~sync~).
+    2. Let _result_ be Completion(IteratorBindingInitialization of |ArrayBindingPattern| with arguments _iteratorRecord_ and _environment_).
+
+    Runtime Semantics: IteratorBindingInitialization (_iteratorRecord_, _environment_)
+
+    BindingElement : BindingPattern Initializer?
+    2. If _iteratorRecord_.[[Done]] is *false*, then
+        a. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
+
+    IteratorStepValue (_iteratorRecord_)
+    1. Let _result_ be ? IteratorStep(_iteratorRecord_).
+
+    IteratorStep (_iteratorRecord_)
+    1. Let _result_ be ? IteratorNext(_iteratorRecord_).
+
+    IteratorNext (_iteratorRecord_, optional _value_)
+    1. If _value_ is not present, then
+        a. Let _result_ be Completion(Call(_iteratorRecord_.[[NextMethod]], _iteratorRecord_.[[Iterator]])).
+    6. Return _result_.
+features: [destructuring-binding, async-functions, async-iteration, Symbol.iterator]
+---*/
+assert.throws(TypeError, function () {
+    var [[] = 1] = { [Symbol.iterator] : async function (x) {}};
+}, "IteratorStepValue throws when iteratorRecord.[[NextMethod]] is undefined.");