testDirectProxyDefinePropertyFailure.js

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// 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);