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function test() {
var from, to;
// Property changes value.
from = {x: 1, y: 2};
to = {set x(v) { from.y = 5; }};
Object.assign(to, from);
assertEq(to.y, 5);
// Property becomes a getter.
from = {x: 1, y: 2};
to = {set x(v) { Object.defineProperty(from, "y", {get: () => 4}); }};
Object.assign(to, from);
assertEq(to.y, 4);
// Property becomes non-enumerable.
from = {x: 1, y: 2};
to = {set x(v) { Object.defineProperty(from, "y", {value: 2,
enumerable: false,
configurable: true,
writable: true}); }};
Object.assign(to, from);
assertEq("y" in to, false);
to = {};
Object.assign(to, from);
assertEq("y" in to, false);
// Property is deleted. Should NOT get Object.prototype.toString.
from = {x: 1, toString: 2};
to = {set x(v) { delete from.toString; }};
Object.assign(to, from);
assertEq(to.hasOwnProperty("toString"), false);
from = {toString: 2, x: 1};
to = {set x(v) { delete from.toString; }};
Object.assign(to, from);
assertEq(to.toString, 2);
from = {x: 1, toString: 2, y: 3};
to = {set x(v) { delete from.toString; }};
Object.assign(to, from);
assertEq(to.hasOwnProperty("toString"), false);
assertEq(to.y, 3);
// New property is added.
from = {x: 1, y: 2};
to = {set x(v) { from.z = 3; }};
Object.assign(to, from);
assertEq("z" in to, false);
// From getter.
var c = 7;
from = {x: 1, get y() { return ++c; }};
to = {};
Object.assign(to, from);
Object.assign(to, from, from);
assertEq(to.y, 10);
// Frozen object.
from = {x: 1, y: 2};
to = {x: 4};
Object.freeze(to);
var ex;
try {
Object.assign(to, from);
} catch (e) {
ex = e;
}
assertEq(ex instanceof TypeError, true);
assertEq(to.x, 4);
// Non-writable property.
from = {x: 1, y: 2, z: 3};
to = {};
Object.defineProperty(to, "y", {value: 9, writable: false});
ex = null;
try {
Object.assign(to, from);
} catch(e) {
ex = e;
}
assertEq(ex instanceof TypeError, true);
assertEq(to.x, 1);
assertEq(to.y, 9);
assertEq(to.z, undefined);
// Array with dense elements.
from = [1, 2, 3];
to = {};
Object.assign(to, from);
assertEq(to[2], 3);
assertEq("length" in to, false);
// Object with sparse elements and symbols.
from = {x: 1, 1234567: 2, 1234560: 3,[Symbol.iterator]: 5, z: 3};
to = {};
Object.assign(to, from);
assertEq(to[1234567], 2);
assertEq(Object.keys(to).toString(), "1234560,1234567,x,z");
assertEq(to[Symbol.iterator], 5);
// Symbol properties need to be assigned last.
from = {x: 1, [Symbol.iterator]: 2, y: 3};
to = {set y(v) { throw 9; }};
ex = null;
try {
Object.assign(to, from);
} catch (e) {
ex = e;
}
assertEq(ex, 9);
assertEq(to.x, 1);
assertEq(to.hasOwnProperty(Symbol.iterator), false);
// Typed array.
from = new Int32Array([1, 2, 3]);
to = {};
Object.assign(to, from);
assertEq(to[1], 2);
// Primitive string.
from = "foo";
to = {};
Object.assign(to, from);
assertEq(to[0], "f");
// String object.
from = new String("bar");
to = {};
Object.assign(to, from);
assertEq(to[2], "r");
}
test();
test();
test();
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