src/third_party/mozjs-45/js/src/jit-test/tests/proxy/testDirectProxyDefinePropertyFailure.js

// Test handling of false return from a handler.defineProperty() hook.

load(libdir + "asserts.js");

var obj = {x: 1, y: 2};
var nope = false;
var p = new Proxy(obj, {
    defineProperty(target, key, desc) { return nope; }
});

// Object.defineProperty throws on failure.
print(1);
assertThrowsInstanceOf(() => Object.defineProperty(p, "z", {value: 3}), TypeError);
assertEq("z" in obj, false);
assertThrowsInstanceOf(() => Object.defineProperty(p, "x", {value: 0}), TypeError);

// Setting a property ultimately causes [[DefineOwnProperty]] to be called.
// In strict mode code only, this is a TypeError.
print(2);
assertEq(p.z = 3, 3);
assertThrowsInstanceOf(() => { "use strict"; p.z = 3; }, TypeError);

// Other falsy values also trigger failure.
print(3);
for (nope of [0, -0, NaN, ""])
    assertThrowsInstanceOf(() => { "use strict"; p.z = 3; }, TypeError);