JSTests/test262/test/language/expressions/generators/dstr-ary-ptrn-elem-id-init-undef.js

// This file was procedurally generated from the following sources:
// - src/dstr-binding/ary-ptrn-elem-id-init-undef.case
// - src/dstr-binding/default/gen-func-expr.template
/*---
description: Destructuring initializer with an undefined value (generator function expression)
esid: sec-generator-function-definitions-runtime-semantics-evaluation
es6id: 14.4.14
features: [generators, destructuring-binding]
flags: [generated]
info: |
    GeneratorExpression : function * ( FormalParameters ) { GeneratorBody }

        [...]
        3. Let closure be GeneratorFunctionCreate(Normal, FormalParameters,
           GeneratorBody, 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.
    [...]

    13.3.3.6 Runtime Semantics: IteratorBindingInitialization

    SingleNameBinding : BindingIdentifier Initializeropt

    [...]
    6. If Initializer is present and v is undefined, then
       a. Let defaultValue be the result of evaluating Initializer.
       b. Let v be GetValue(defaultValue).
       [...]
    7. If environment is undefined, return PutValue(lhs, v).
    8. Return InitializeReferencedBinding(lhs, v).
---*/

var callCount = 0;
var f;
f = function*([x = 23]) {
  assert.sameValue(x, 23);
  callCount = callCount + 1;
};

f([undefined]).next();
assert.sameValue(callCount, 1, 'generator function invoked exactly once');