Add Object.create from ECMAScript5. Supports value, writable, enumerable, ge...

test/mjsunit/object-create.js

+// Copyright 2009 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test ES5 sections 15.2.3.5 Object.create.
+// We do not support nonconfigurable properties on objects so that is not
+// tested.  We do test getters, setters, writable, enumerable and value.
+
+// Check that no exceptions are thrown.
+Object.create(null);
+Object.create(null, undefined);
+
+var ctr = 0;
+var ctr2 = 0;
+var ctr3 = 0;
+var ctr4 = 0;
+var ctr5 = 0;
+var ctr6 = 1000;
+
+var foo_proto = { foo: function() { ctr++; }};

[Christian Plesner Hansen, 2009/12/08 20:44:40]

lowerCamelCase.

+var fooValue = { foo: { writable: true, value: function() { ctr2++; }}};
+var fooGetter = { foo: { get: function() { return ctr3++; }}};
+var fooSetter = { foo: { set: function() { return ctr4++; }}};
+var fooAmbiguous = { foo: { get: function() { return ctr3++; },
+                            value: 3 }};
+
+function valueGet() { ctr5++; return 3 };
+function getterGet() { ctr5++; return function() { return ctr6++; }; };
+
+// Simple object with prototype, no properties added.
+Object.create(foo_proto).foo();
+assertEquals(1, ctr);
+
+// Simple object with object with prototype, no properties added.
+Object.create(Object.create(foo_proto)).foo();
+assertEquals(2, ctr);
+
+// Add a property foo that returns a function.
+var v = Object.create(foo_proto, fooValue);
+v.foo();
+assertEquals(2, ctr);
+assertEquals(1, ctr2);
+
+// Ensure the property is writable.
+v.foo = 42;
+assertEquals(42, v.foo);
+assertEquals(2, ctr);
+assertEquals(1, ctr2);
+
+// Ensure by default properties are not writable.
+v = Object.create(null, { foo: {value: 103}});
+assertEquals(103, v.foo);
+v.foo = 42;
+assertEquals(103, v.foo);
+
+// Add a getter foo that returns a counter value.
+assertEquals(0, Object.create(foo_proto, fooGetter).foo);
+assertEquals(2, ctr);
+assertEquals(1, ctr2);
+assertEquals(1, ctr3);
+
+// Add a setter foo that runs a function.
+assertEquals(1, Object.create(foo_proto, fooSetter).foo = 1);
+assertEquals(2, ctr);
+assertEquals(1, ctr2);
+assertEquals(1, ctr3);
+assertEquals(1, ctr4);
+
+// Make sure that trying to add both a value and a getter
+// will result in an exception.
+try {
+  Object.create(foo_proto, fooAmbiguous);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Invalid property/.test(e));
+}
+assertEquals(2, ctr);
+assertEquals(1, ctr2);
+assertEquals(1, ctr3);
+assertEquals(1, ctr4);
+
+var ctr7 = 0;
+
+var metaProps = {
+  enumerable: { get: function() {
+                       assertEquals(0, ctr7++);
+                       return true;
+                     }},
+  configurable: { get: function() {
+                         assertEquals(1, ctr7++);
+                         return true;
+                       }},
+  value: { get: function() {
+                  assertEquals(2, ctr7++);
+                  return 4;
+                }},
+  writable: { get: function() {
+                     assertEquals(3, ctr7++);
+                     return true;
+                   }},
+  get: { get: function() {
+                assertEquals(4, ctr7++);
+                return function() { };
+              }},
+  set: { get: function() {
+                assertEquals(5, ctr7++);
+                return function() { };
+              }}
+};
+
+
+// Instead of a plain props object, let's use getters to return its properties.
+var magicValueProps = { foo: Object.create(null, { value: { get: valueGet }})};
+var magicGetterProps = { foo: Object.create(null, { get: { get: getterGet }})};
+var magicAmbiguousProps = { foo: Object.create(null, metaProps) };
+
+assertEquals(3, Object.create(null, magicValueProps).foo);
+assertEquals(1, ctr5);
+
+assertEquals(1000, Object.create(null, magicGetterProps).foo);
+assertEquals(2, ctr5);
+
+// See if we do the steps in ToPropertyDescriptor in the right order.
+// We shouldn't throw the exception for an ambiguous properties object
+// before we got all the values out.
+try {
+  Object.create(null, magicAmbiguousProps);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Invalid property/.test(e));
+  assertEquals(6, ctr7);
+}
+
+var magicWritableProps = {
+  foo: Object.create(null, { value: { value: 4 },
+                             writable: { get: function() {
+                                                ctr6++;
+                                                return false;
+                                              }}})};
+
+var fooNotWritable = Object.create(null, magicWritableProps)
+assertEquals(1002, ctr6);
+assertEquals(4, fooNotWritable.foo);
+fooNotWritable.foo = 5;
+assertEquals(4, fooNotWritable.foo);
+
+
+// Test enumerable flag.
+
+var fooNotEnumerable =
+    Object.create({fizz: 14}, {foo: {value: 3, enumerable: false},
+                               bar: {value: 4, enumerable: true},
+                               baz: {value: 5}});
+var sum = 0;
+for (x in fooNotEnumerable) {
+  assertTrue(x === 'bar' || x === 'fizz');
+  sum += fooNotEnumerable[x];
+}
+assertEquals(18, sum);
+
+
+try {
+  Object.create(null, {foo: { get: 0 }});
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Getter must be a function/.test(e));
+}
+
+try {
+  Object.create(null, {foo: { set: 0 }});
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Setter must be a function/.test(e));
+}
+
+try {
+  Object.create(null, {foo: { set: 0, get: 0 }});
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Getter must be a function/.test(e));
+}
+
+
+// Ensure that only enumerable own properties on the descriptor are used.
+var tricky = Object.create(
+  { foo: { value: 1, enumerable: true }},
+  { bar: { value: { value: 2, enumerable: true }, enumerable: false },
+    baz: { value: { value: 4, enumerable: false }, enumerable: true },
+    fizz: { value: { value: 8, enumerable: false }, enumerable: false },
+    buzz: { value: { value: 16, enumerable: true }, enumerable: true }});
+
+assertEquals(1, tricky.foo.value);
+assertEquals(2, tricky.bar.value);
+assertEquals(4, tricky.baz.value);
+assertEquals(8, tricky.fizz.value);
+assertEquals(16, tricky.buzz.value);
+
+var sonOfTricky = Object.create(null, tricky);
+
+assertFalse("foo" in sonOfTricky);
+assertFalse("bar" in sonOfTricky);
+assertTrue("baz" in sonOfTricky);
+assertFalse("fizz" in sonOfTricky);
+assertTrue("buzz" in sonOfTricky);
+
+var sum = 0;
+for (x in sonOfTricky) {
+  assertTrue(x === 'buzz');
+  sum += sonOfTricky[x];
+}
+assertEquals(16, sum);