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// |reftest| skip -- set-methods is not supported
// Copyright (C) 2023 Anthony Frehner. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-set.prototype.union
description: Set.prototype.union works on subclasses of Set, but returns an instance of Set
features: [set-methods]
includes: [compareArray.js]
---*/
class MySet extends Set {}
const s1 = new MySet([1, 2]);
const s2 = new Set([2, 3]);
const expected = [1, 2, 3];
const combined = s1.union(s2);
assert.compareArray([...combined], expected);
assert.sameValue(combined instanceof Set, true, "The returned object is a Set");
assert.sameValue(
combined instanceof MySet,
false,
"The returned object is a Set, not a subclass"
);
reportCompare(0, 0);
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