propertyIsEnumerable-proxy.js

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/* Any copyright is dedicated to the Public Domain.

 * http://creativecommons.org/publicdomain/zero/1.0/ */

function logProxy(object) {

    var log = [];

    var handler = {

        getOwnPropertyDescriptor(target, propertyKey) {

            log.push(propertyKey);

            return Object.getOwnPropertyDescriptor(target, propertyKey);

};

    var proxy = new Proxy(object, new Proxy(handler, {

        get(target, propertyKey, receiver) {

            if (!(propertyKey in target)) {

                throw new Error(`Unexpected call to trap: "${propertyKey}"`);

            return target[propertyKey];

    }));

    return {proxy, log};

var properties = ["string-property"];

if (typeof Symbol === 'function')

    properties.push(Symbol("symbol-property"));

for (var property of properties) {

    // Test 1: property is not present on object

    var {proxy, log} = logProxy({});

    var result = Object.prototype.propertyIsEnumerable.call(proxy, property);

    assertEq(result, false);

    assertDeepEq(log, [property]);

    // Test 2: property is present on object and enumerable

    var {proxy, log} = logProxy({[property]: 0});

    var result = Object.prototype.propertyIsEnumerable.call(proxy, property);

    assertEq(result, true);

    assertDeepEq(log, [property]);

    // Test 3: property is present on object, but not enumerable

    var {proxy, log} = logProxy(Object.defineProperty({[property]: 0}, property, {enumerable: false}));

    var result = Object.prototype.propertyIsEnumerable.call(proxy, property);

    assertEq(result, false);

    assertDeepEq(log, [property]);

    // Test 4: property is present on prototype object

    var {proxy, log} = logProxy(Object.create({[property]: 0}));

    var result = Object.prototype.propertyIsEnumerable.call(proxy, property);

    assertEq(result, false);

    assertDeepEq(log, [property]);

    // Test 5: property is present on prototype object, prototype is proxy object

    var {proxy, log} = logProxy({[property]: 0});

    var result = Object.prototype.propertyIsEnumerable.call(Object.create(proxy), property);

    assertEq(result, false);

    assertDeepEq(log, []);

reportCompare(0, 0);