[esnext] implement Object.getOwnPropertyDescriptors() proposal

test/mjsunit/harmony/object-get-own-property-descriptors.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-object-own-property-descriptors
+// Flags: --harmony-proxies --harmony-reflect --allow-natives-syntax
+
+function DataDescriptor(value) {
+  return { "enumerable": true, "configurable": true, "writable": true, value };
+}
+
+
+function TestMeta() {
+  assertEquals(1, Object.getOwnPropertyDescriptors.length);
+  assertEquals(Function.prototype,
+               Object.getPrototypeOf(Object.getOwnPropertyDescriptors));
+  assertEquals(
+      'getOwnPropertyDescriptors', Object.getOwnPropertyDescriptors.name);
+  var desc = Reflect.getOwnPropertyDescriptor(
+      Object, 'getOwnPropertyDescriptors');
+  assertFalse(desc.enumerable);
+  assertTrue(desc.writable);
+  assertTrue(desc.configurable);
+}
+TestMeta();
+
+
+function TestToObject() {
+  assertThrows(function() {
+    Object.getOwnPropertyDescriptors(null);
+  }, TypeError);
+
+  assertThrows(function() {
+    Object.getOwnPropertyDescriptors(undefined);
+  }, TypeError);
+
+  assertThrows(function() {
+    Object.getOwnPropertyDescriptors();
+  }, TypeError);
+}
+TestToObject();
+
+
+function TestPrototypeProperties() {
+  function F() {};
+  F.prototype.a = "A";
+  F.prototype.b = "B";
+
+  var F2 = new F();
+  Object.defineProperties(F2, {
+    "b": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "Shadowed 'B'"
+    },
+    "c": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "C"
+    }
+  });
+
+  assertEquals({
+    "b": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "Shadowed 'B'"
+    },
+    "c": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "C"
+    }
+  }, Object.getOwnPropertyDescriptors(F2));
+}
+TestPrototypeProperties();
+
+
+function TestPrototypeProperties() {
+  function F() {};
+  F.prototype.a = "A";
+  F.prototype.b = "B";
+
+  var F2 = new F();
+  Object.defineProperties(F2, {
+    "b": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "Shadowed 'B'"
+    },
+    "c": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "C"
+    }
+  });
+
+  assertEquals({
+    "b": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "Shadowed 'B'"
+    },
+    "c": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "C"
+    }
+  }, Object.getOwnPropertyDescriptors(F2));
+}
+TestPrototypeProperties();
+
+
+function TestTypeFilteringAndOrder() {
+  var log = [];
+  var sym = Symbol("foo");
+  var psym = %CreatePrivateSymbol("private");
+  var O = {
+    0: 0,
+    [sym]: 3,
+    "a": 2,
+    [psym]: 4,
+    1: 1,
+  };
+  var P = new Proxy(O, {
+    ownKeys(target) {
+      log.push("ownKeys()");
+      return Reflect.ownKeys(target);
+    },
+    getOwnPropertyDescriptor(target, name) {
+      log.push(`getOwnPropertyDescriptor(${String(name)})`);
+      return Reflect.getOwnPropertyDescriptor(target, name);
+    },
+    get(target, name) { assertUnreachable(); },
+    set(target, name, value) { assertUnreachable(); },
+    deleteProperty(target, name) { assertUnreachable(); },
+    defineProperty(target, name, desc) { assertUnreachable(); }
+  });
+
+  var result1 = Object.getOwnPropertyDescriptors(O);
+  assertEquals({
+    0: DataDescriptor(0),
+    1: DataDescriptor(1),
+    "a": DataDescriptor(2),
+    [sym]: DataDescriptor(3)
+  }, result1);
+
+  var result2 = Object.getOwnPropertyDescriptors(P);
+  assertEquals([
+    "ownKeys()",
+    "getOwnPropertyDescriptor(0)",
+    "getOwnPropertyDescriptor(1)",
+    "getOwnPropertyDescriptor(a)",
+    "getOwnPropertyDescriptor(Symbol(foo))"
+  ], log);
+  assertEquals({
+    0: DataDescriptor(0),
+    1: DataDescriptor(1),
+    "a": DataDescriptor(2),
+    [sym]: DataDescriptor(3)
+  }, result2);
+}
+TestTypeFilteringAndOrder();
+
+
+function TestDuplicateKeys() {
+  var i = 0;
+  var log = [];
+  var P = new Proxy({}, {
+    ownKeys() {
+      log.push(`ownKeys()`);
+      return ["A", "A"];
+    },
+    getOwnPropertyDescriptor(t, name) {
+      log.push(`getOwnPropertyDescriptor(${name})`);
+      if (i++) return;
+      return {
+        configurable: true,
+        writable: false,
+        value: "VALUE"
+      };
+    },
+    get(target, name) { assertUnreachable(); },
+    set(target, name, value) { assertUnreachable(); },
+    deleteProperty(target, name) { assertUnreachable(); },
+    defineProperty(target, name, desc) { assertUnreachable(); }
+  });
+
+  var result = Object.getOwnPropertyDescriptors(P);
+  assertEquals({ "A": undefined }, result);
+  assertTrue(result.hasOwnProperty("A"));
+  assertEquals([
+    "ownKeys()",
+    "getOwnPropertyDescriptor(A)",
+    "getOwnPropertyDescriptor(A)"
+  ], log);
+}
+TestDuplicateKeys();