test262/test/language/statements/for/dstr-let-ary-ptrn-elision.js

// This file was procedurally generated from the following sources:
// - src/dstr-binding/ary-ptrn-elision.case
// - src/dstr-binding/default/for-let.template
/*---
description: Elision advances iterator (for statement)
esid: sec-for-statement-runtime-semantics-labelledevaluation
es6id: 13.7.4.7
features: [generators, destructuring-binding]
flags: [generated]
info: |
    IterationStatement :
        for ( LexicalDeclaration Expressionopt ; Expressionopt ) Statement

    [...]
    7. Let forDcl be the result of evaluating LexicalDeclaration.
    [...]

    LexicalDeclaration : LetOrConst BindingList ;

    1. Let next be the result of evaluating BindingList.
    2. ReturnIfAbrupt(next).
    3. Return NormalCompletion(empty).

    BindingList : BindingList , LexicalBinding

    1. Let next be the result of evaluating BindingList.
    2. ReturnIfAbrupt(next).
    3. Return the result of evaluating LexicalBinding.

    LexicalBinding : BindingPattern Initializer

    1. Let rhs be the result of evaluating Initializer.
    2. Let value be GetValue(rhs).
    3. ReturnIfAbrupt(value).
    4. Let env be the running execution context’s LexicalEnvironment.
    5. Return the result of performing BindingInitialization for BindingPattern
       using value and env as the arguments.

    13.3.3.6 Runtime Semantics: IteratorBindingInitialization

    ArrayBindingPattern : [ Elision ]

    1. Return the result of performing
       IteratorDestructuringAssignmentEvaluation of Elision with iteratorRecord
       as the argument.

    12.14.5.3 Runtime Semantics: IteratorDestructuringAssignmentEvaluation

    Elision : ,

    1. If iteratorRecord.[[done]] is false, then
       a. Let next be IteratorStep(iteratorRecord.[[iterator]]).
       b. If next is an abrupt completion, set iteratorRecord.[[done]] to true.
       c. ReturnIfAbrupt(next).
       d. If next is false, set iteratorRecord.[[done]] to true.
    2. Return NormalCompletion(empty).

---*/
var first = 0;
var second = 0;
function* g() {
  first += 1;
  yield;
  second += 1;
};

var iterCount = 0;

for (let [,] = g(); iterCount < 1; ) {
  assert.sameValue(first, 1);
  assert.sameValue(second, 0);

  iterCount += 1;
}

assert.sameValue(iterCount, 1, 'Iteration occurred as expected');