src/dstr-assignment/array-elem-iter-rtrn-close-null.case

// Copyright (C) 2016 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
desc: >
    IteratorClose throws a TypeError when `return` returns a non-Object value
info: |
    ArrayAssignmentPattern : [ AssignmentElementList ]

    [...]
    5. If iteratorRecord.[[done]] is false, return IteratorClose(iterator,
       result).
    6. Return result.

    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).
    9. If Type(innerResult.[[value]]) is not Object, throw a TypeError
       exception.
features: [Symbol.iterator, generators]
template: default
esid: sec-runtime-semantics-destructuringassignmentevaluation
---*/

//- setup
var nextCount = 0;
var returnCount = 0;
var unreachable = 0;
var iterator = {
  next: function() {
    nextCount += 1;
    return {done: false, value: undefined};
  },
  return: function() {
    returnCount += 1;
    return null;
  }
};
var iterable = {};
iterable[Symbol.iterator] = function() {
  return iterator;
};
function* g() {
//- elems
[ {} = yield ]
//- vals
iterable
//- body
  unreachable += 1;
//- teardown
}

var iter = g();
iter.next();

assert.sameValue(nextCount, 1);
assert.sameValue(returnCount, 0);
assert.throws(TypeError, function() {
  iter.return();
});
assert.sameValue(nextCount, 1);
assert.sameValue(returnCount, 1);
assert.sameValue(unreachable, 0, 'Unreachable statement was not executed');