test262/test/language/expressions/function/dstr/dflt-ary-init-iter-close.js

// This file was procedurally generated from the following sources:
// - src/dstr-binding/ary-init-iter-close.case
// - src/dstr-binding/default/func-expr-dflt.template
/*---
description: Iterator is closed when not exhausted by pattern evaluation (function expression (default parameter))
esid: sec-function-definitions-runtime-semantics-evaluation
features: [Symbol.iterator, destructuring-binding, default-parameters]
flags: [generated]
info: |
    FunctionExpression : function ( FormalParameters ) { FunctionBody }

        [...]
        3. Let closure be FunctionCreate(Normal, FormalParameters, FunctionBody,
           scope, strict).
        [...]

    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.
    [...]

    13.3.3.5 Runtime Semantics: BindingInitialization

    BindingPattern : ArrayBindingPattern

    [...]
    4. If iteratorRecord.[[done]] is false, return ? IteratorClose(iterator,
       result).
    [...]

---*/
var doneCallCount = 0;
var iter = {};
iter[Symbol.iterator] = function() {
  return {
    next: function() {
      return { value: null, done: false };
    },
    return: function() {
      doneCallCount += 1;
      return {};
    }
  };
};

var callCount = 0;
var f;
f = function([x] = iter) {
  assert.sameValue(doneCallCount, 1);
  callCount = callCount + 1;
};

f();
assert.sameValue(callCount, 1, 'function invoked exactly once');