JSTests/test262/test/language/expressions/object/dstr/meth-dflt-ary-ptrn-elision.js

// This file was procedurally generated from the following sources:
// - src/dstr-binding/ary-ptrn-elision.case
// - src/dstr-binding/default/meth-dflt.template
/*---
description: Elision advances iterator (method (default parameter))
esid: sec-runtime-semantics-definemethod
features: [generators, destructuring-binding, default-parameters]
flags: [generated]
info: |
    MethodDefinition : PropertyName ( StrictFormalParameters ) { FunctionBody }

    [...]
    6. Let closure be FunctionCreate(kind, StrictFormalParameters,
       FunctionBody, scope, strict). If functionPrototype was passed as a
       parameter then pass its value as the functionPrototype optional argument
       of FunctionCreate.
    [...]

    9.2.1 [[Call]] ( thisArgument, argumentsList)

    [...]
    7. Let result be OrdinaryCallEvaluateBody(F, argumentsList).
    [...]

    9.2.1.3 OrdinaryCallEvaluateBody ( F, argumentsList )

    1. Let status be FunctionDeclarationInstantiation(F, argumentsList).
    [...]

    9.2.12 FunctionDeclarationInstantiation(func, argumentsList)

    [...]
    23. Let iteratorRecord be Record {[[iterator]]:
        CreateListIterator(argumentsList), [[done]]: false}.
    24. If hasDuplicates is true, then
        [...]
    25. Else,
        b. Let formalStatus be IteratorBindingInitialization for formals with
           iteratorRecord and env as 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 callCount = 0;
var obj = {
  method([,] = g()) {
    assert.sameValue(first, 1);
    assert.sameValue(second, 0);
    callCount = callCount + 1;
  }
};

obj.method();
assert.sameValue(callCount, 1, 'method invoked exactly once');