test_array_proto_subclassing.cjs
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test_array_proto_subclassing.cjs
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	function assert(cond, msg) {
	if (!cond) throw new Error(msg);
	}

	console.log("array prototype and subclassing regression");

	assert(Array.isArray(Array.prototype), "Array.prototype should be an array exotic");
	assert(Object.getPrototypeOf(Array.prototype) === Object.prototype, "Array.prototype should inherit from Object.prototype");

	class C extends Array {}
	const c = new C(1, 2, 3);

	assert(c instanceof C, "Array subclass instances should preserve subclass identity");
	assert(c instanceof Array, "Array subclass instances should still be arrays");
	assert(c.concat(4) instanceof C, "concat should preserve Array subclass");
	assert(c.map(x => x) instanceof C, "map should preserve Array subclass");
	assert(c.filter(() => true) instanceof C, "filter should preserve Array subclass");
	assert(c.slice(0) instanceof C, "slice should preserve Array subclass");
	assert(C.from([1, 2]) instanceof C, "Array.from on subclass should preserve subclass");
	assert(C.of(1, 2) instanceof C, "Array.of on subclass should preserve subclass");

	console.log("PASS");