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// Tests for Object.assign's fast path for plain objects.
load(libdir + "asserts.js");
function testProtoSetter() {
var from = Object.create(null);
from.__proto__ = {};
assertEq(Object.getPrototypeOf(from), null);
var to = Object.assign({}, from);
assertEq(Object.getPrototypeOf(to), from.__proto__);
assertEq(Object.getOwnPropertyNames(to).length, 0);
}
testProtoSetter();
function testProtoDataProp() {
var to = Object.create(null);
to.__proto__ = 1;
var from = Object.create(null);
from.__proto__ = 2;
Object.assign(to, from);
assertEq(Object.getPrototypeOf(to), null);
assertEq(to.__proto__, 2);
}
testProtoDataProp();
function testNonExtensible() {
var to = Object.preventExtensions({x: 1});
Object.assign(to, {x: 2});
assertEq(to.x, 2);
assertThrowsInstanceOf(() => Object.assign(to, {x: 3, y: 4}), TypeError);
assertEq(to.x, 3);
assertEq("y" in to, false);
}
testNonExtensible();
function testNonExtensibleNoProps() {
var to = Object.preventExtensions({});
Object.assign(to, {}); // No exception.
}
testNonExtensibleNoProps();
function testDenseElements() {
var to = Object.assign({}, {0: 1, 1: 2});
assertEq(to[0], 1);
assertEq(to[1], 2);
}
testDenseElements();
function testNonWritableOnProto() {
var proto = {};
Object.defineProperty(proto, "x", {value: 1, enumerable: true, configurable: true});
var to = Object.create(proto);
assertThrowsInstanceOf(() => Object.assign(to, {x: 2}), TypeError);
assertEq(to.x, 1);
assertEq(Object.getOwnPropertyNames(to).length, 0);
}
testNonWritableOnProto();
function testAccessorOnProto() {
var setterVal;
var proto = {set a(v) { setterVal = v; }};
var to = Object.assign(Object.create(proto), {a: 9});
assertEq(setterVal, 9);
assertEq(Object.getOwnPropertyNames(to).length, 0);
}
testAccessorOnProto();
function testSetAndAdd() {
var to = Object.assign({x: 1, y: 2}, {x: 3, y: 4, z: 5});
assertEq(to.x, 3);
assertEq(to.y, 4);
assertEq(to.z, 5);
}
testSetAndAdd();
function testNonConfigurableFrom() {
var from = {};
Object.defineProperty(from, "x", {value: 1, enumerable: true, writable: true});
var to = Object.assign({}, from);
assertEq(to.x, 1);
assertEq(Object.getOwnPropertyDescriptor(to, "x").configurable, true);
}
testNonConfigurableFrom();
function testNonEnumerableFrom() {
var from = {};
Object.defineProperty(from, "x", {value: 1, configurable: true, writable: true});
var to = Object.assign({}, from);
assertEq(Object.getOwnPropertyNames(to).length, 0);
assertEq(to.x, undefined);
}
testNonEnumerableFrom();
function testNonWritableFrom() {
var from = {};
Object.defineProperty(from, "x", {value: 1, configurable: true, enumerable: true});
var to = Object.assign({}, from);
assertEq(to.x, 1);
assertEq(Object.getOwnPropertyDescriptor(to, "x").writable, true);
}
testNonWritableFrom();
function testFrozenProto() {
var proto = Object.freeze({x: 1});
var target = Object.create(proto);
Object.assign(target, {foo: 1});
assertEq(target.foo, 1);
assertThrowsInstanceOf(() => Object.assign(target, {x: 2}), TypeError);
assertEq(target.x, 1);
}
testFrozenProto();
function testReuseShape() {
var from = {};
from.x = 1;
from.y = 2;
var to = Object.assign({}, from);
assertEq(to.x, 1);
assertEq(to.y, 2);
}
testReuseShape();
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