Add test case where IteratorBindingInitialization throws when evaluating initializer

test/language/destructuring/binding/initializer-evaluation-throws-identifier.js

@@ -0,0 +1,50 @@
+// 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: >
+    IteratorBindingInitialization throws ReferenceError when evaluating an unresolvable Initializer.
+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?
+    1. Let _v_ be *undefined*.
+    2. If _iteratorRecord_.[[Done]] is *false*, then
+        a. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
+        b. If _next_ is not ~done~, then
+            i. Set _v_ to _next_.
+    3. If |Initializer| is present and _v_ is *undefined*, then
+        a. Let _defaultValue_ be ? Evaluation of |Initializer|.
+        b. Set _v_ to ? GetValue(_defaultValue_).
+
+    Runtime Semantics: Evaluation
+    IdentifierReference : Identifier
+    1. Return ? ResolveBinding(StringValue of |Identifier|).
+
+    ResolveBinding (_name_, optional _env_)
+    4. Return ? GetIdentifierReference(_env_, _name_, _strict_).
+
+    GetIdentifierReference (_env_, _name_, _strict_)
+    1. If _env_ is *null*, then
+        a. Return the Reference Record { [[Base]]: ~unresolvable~, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
+    4. Else,
+        a. Let _outer_ be _env_.[[OuterEnv]].
+        b. Return ? GetIdentifierReference(_outer_, _name_, _strict_).      
+
+    GetValue (_V_)
+    2. If IsUnresolvableReference(_V_) is *true*, throw a *ReferenceError* exception.
+
+    IsUnresolvableReference (_V_)
+    1. If _V_.[[Base]] is ~unresolvable~, return *true*; otherwise return *false*.
+features: [destructuring-binding]
+---*/
+assert.throws(ReferenceError, function () {
+    var [{} = x] = ''
+}, "IteratorBindingInitialization throws ReferenceError when evaluating an unresolvable Initializer.")

test/language/destructuring/binding/initializer-evaluation-throws-unaryexpression.js

@@ -0,0 +1,55 @@
+// 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: >
+    IteratorBindingInitialization throws ReferenceError when evaluating an unresolvable Initializer.
+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?
+    1. Let _v_ be *undefined*.
+    2. If _iteratorRecord_.[[Done]] is *false*, then
+        a. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
+        b. If _next_ is not ~done~, then
+            i. Set _v_ to _next_.
+    3. If |Initializer| is present and _v_ is *undefined*, then
+        a. Let _defaultValue_ be ? Evaluation of |Initializer|.
+        b. Set _v_ to ? GetValue(_defaultValue_).
+
+    Runtime Semantics: Evaluation
+    UnaryExpression : `+` UnaryExpression
+    1. Let _expr_ be ? Evaluation of |UnaryExpression|.
+    2. Return ? ToNumber(? GetValue(_expr_)).
+
+    Runtime Semantics: Evaluation
+    IdentifierReference : Identifier
+    1. Return ? ResolveBinding(StringValue of |Identifier|).
+
+    ResolveBinding (_name_, optional _env_)
+    4. Return ? GetIdentifierReference(_env_, _name_, _strict_).
+
+    GetIdentifierReference (_env_, _name_, _strict_)
+    1. If _env_ is *null*, then
+        a. Return the Reference Record { [[Base]]: ~unresolvable~, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
+    4. Else,
+        a. Let _outer_ be _env_.[[OuterEnv]].
+        b. Return ? GetIdentifierReference(_outer_, _name_, _strict_).      
+
+    GetValue (_V_)
+    2. If IsUnresolvableReference(_V_) is *true*, throw a *ReferenceError* exception.
+
+    IsUnresolvableReference (_V_)
+    1. If _V_.[[Base]] is ~unresolvable~, return *true*; otherwise return *false*.
+features: [destructuring-binding]
+---*/
+assert.throws(ReferenceError, function () {
+    var [{} = + x] = ''
+}, "IteratorBindingInitialization throws ReferenceError when evaluating an unresolvable Initializer.")