extendBuiltinConstructors.js

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function testBuiltinInstanceIsInstanceOf(instance, builtin, class_) {

    assertEq(instance instanceof class_, true);

    assertEq(instance instanceof builtin, true);

    if (builtin === Array)

        assertEq(Array.isArray(instance), true);

function testBuiltinInstance(builtin, ...args) {

    class sub extends builtin {

        constructor(...args) {

            super(...args);

            this.called = true;

    let instance = new sub(...args);

    assertEq(instance.called, true);

    testBuiltinInstanceIsInstanceOf(instance, builtin, sub);

function testBuiltinMultipleSubclasses(builtin, ...args) {

    function f(obj, prop) {

        assertEq(obj.prop, prop);

    class sub1 extends builtin { };

    class sub2 extends builtin { };

    const prop1 = "A";

    const prop2 = "B";

    sub1.prototype.prop = prop1;

    sub2.prototype.prop = prop2;

    let instance1 = new sub1(...args);

    let instance2 = new sub2(...args);

    // Also make sure we get the properties we want with a default constructor

    testBuiltinInstanceIsInstanceOf(instance1, builtin, sub1);

    for (let i = 0; i < 10; i++) {

        f(instance1, prop1);

        f(instance2, prop2);

function testBuiltin(builtin, ...args) {

    testBuiltinInstance(builtin, ...args);

    testBuiltinMultipleSubclasses(builtin, ...args);

function testBuiltinTypedArrays() {

    let typedArrays = [Int8Array,

                       Uint8Array,

                       Uint8ClampedArray,

                       Int16Array,

                       Uint16Array,

                       Int32Array,

                       Uint32Array,

                       Float32Array,

                       Float64Array];

    for (let array of typedArrays) {

        testBuiltin(array);

        testBuiltin(array, 5);

        testBuiltin(array, new array());

        testBuiltin(array, new ArrayBuffer());

testBuiltin(Function);

testBuiltin(Object);

testBuiltin(Boolean);

testBuiltin(Error);

testBuiltin(EvalError);

testBuiltin(RangeError);

testBuiltin(ReferenceError);

testBuiltin(SyntaxError);

testBuiltin(TypeError);

testBuiltin(URIError);

testBuiltin(Number);

testBuiltin(Date);

testBuiltin(Date, 5);

testBuiltin(Date, 5, 10);

testBuiltin(RegExp);

testBuiltin(RegExp, /Regexp Argument/);

testBuiltin(RegExp, "String Argument");

testBuiltin(Map);

testBuiltin(Set);

testBuiltin(WeakMap);

testBuiltin(WeakSet);

testBuiltin(ArrayBuffer);

testBuiltinTypedArrays();

testBuiltin(DataView, new ArrayBuffer());

testBuiltin(DataView, new (newGlobal().ArrayBuffer)());

testBuiltin(String);

testBuiltin(Array);

testBuiltin(Array, 15);

testBuiltin(Array, 3.0);

testBuiltin(Array, "non-length one-arg");

testBuiltin(Array, 5, 10, 15, "these are elements");

// More Promise subclassing tests can be found in non262/Promise/promise-subclassing.js

testBuiltin(Promise, _=>{});

if (this.SharedArrayBuffer)

    testBuiltin(SharedArrayBuffer);

if (typeof reportCompare === 'function')

    reportCompare(0,0,"OK");