js/src/tests/test262/built-ins/Set/prototype/forEach/this-arg-explicit-cannot-override-lexical-this-arrow.js


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// Copyright (C) 2015 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-set.prototype.forEach
description: >
    Set.prototype.forEach ( callbackfn [ , thisArg ] )

    ...
    5. If thisArg was supplied, let T be thisArg; else let T be undefined.
    ...

    An arrow function will ignore an explicit thisArg

features: [arrow-function]
---*/

var s = new Set([1]);
var usurper = {};
var counter = 0;

s.forEach(_ => {
  assert.notSameValue(this, usurper, "`this` is not `usurper`");
  counter++;
}, usurper);

assert.sameValue(counter, 1, "`forEach` is not a no-op");

reportCompare(0, 0);