JSTests/test262/test/language/statements/for-of/dstr/array-elem-trlg-iter-rest-rtrn-close.js

// This file was procedurally generated from the following sources:
// - src/dstr-assignment/array-elem-trlg-iter-rest-rtrn-close.case
// - src/dstr-assignment/default/for-of.template
/*---
description: IteratorClose is called when AssignmentRestEvaluation produces a "return" completion due to reference evaluation (For..of statement)
esid: sec-for-in-and-for-of-statements-runtime-semantics-labelledevaluation
features: [Symbol.iterator, generators, destructuring-binding]
flags: [generated]
info: |
    IterationStatement :
      for ( LeftHandSideExpression of AssignmentExpression ) Statement

    1. Let keyResult be the result of performing ? ForIn/OfHeadEvaluation(« »,
       AssignmentExpression, iterate).
    2. Return ? ForIn/OfBodyEvaluation(LeftHandSideExpression, Statement,
       keyResult, assignment, labelSet).

    13.7.5.13 Runtime Semantics: ForIn/OfBodyEvaluation

    [...]
    4. If destructuring is true and if lhsKind is assignment, then
       a. Assert: lhs is a LeftHandSideExpression.
       b. Let assignmentPattern be the parse of the source text corresponding to
          lhs using AssignmentPattern as the goal symbol.
    [...]

    ArrayAssignmentPattern :
        [ AssignmentElementList , Elisionopt AssignmentRestElementopt ]

    [...]
    7. If AssignmentRestElement is present, then
       a. Let status be the result of performing
          IteratorDestructuringAssignmentEvaluation of AssignmentRestElement
          with iteratorRecord as the argument.
    8. If iteratorRecord.[[done]] is false, return IteratorClose(iterator,
       status).
    9. Return Completion(status).

    7.4.6 IteratorClose( iterator, completion )

    [...]
    6. Let innerResult be Call(return, iterator, « »).
    7. If completion.[[type]] is throw, return Completion(completion).
    8. If innerResult.[[type]] is throw, return Completion(innerResult).

---*/
var nextCount = 0;
var returnCount = 0;
var unreachable = 0;
var thisValue = null;
var args = null;
var iterable = {};
var x;
var iterator = {
  next: function() {
    nextCount += 1;
    // Set an upper-bound to limit unnecessary iteration in non-conformant
    // implementations
    return { done: nextCount > 10 };
  },
  return: function() {
    returnCount += 1;
    thisValue = this;
    args = arguments;
    return {};
  }
};
var iter, result;
iterable[Symbol.iterator] = function() {
  return iterator;
};

function* g() {

var counter = 0;

for ([ x , ...{}[yield] ] of [iterable]) {
  unreachable += 1;
  counter += 1;
}

assert.sameValue(counter, 1);

}

iter = g();
iter.next();
result = iter.return(999);

assert.sameValue(nextCount, 1);
assert.sameValue(returnCount, 1);
assert.sameValue(unreachable, 0, 'Unreachable statement was not executed');
assert.sameValue(result.value, 999);
assert(result.done, 'Iterator correctly closed');
assert.sameValue(thisValue, iterator, 'correct `this` value');
assert(!!args, 'arguments object provided');
assert.sameValue(args.length, 0, 'zero arguments specified');