Implement ES5 Object.seal and Object.isSealed....

test/mjsunit/object-seal.js

+// Copyright 2010 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:
+//
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+//     * Redistributions in binary form must reproduce the above
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+// 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.
+
+// Tests the Object.seal and Object.isSealed methods - ES 15.2.3.9 and
+// ES 15.2.3.12
+
+
+// Test that we throw an error if an object is not passed as argument.
+var non_objects = new Array(undefined, null, 1, -1, 0, 42.43);
+for (var key in non_objects) {
+  try {
+    Object.seal(non_objects[key]);
+    assertUnreachable();
+  } catch(e) {
+    assertTrue(/Object.seal called on non-object/.test(e));
+  }
+}
+
+for (var key in non_objects) {
+  try {
+    Object.isSealed(non_objects[key]);
+    assertUnreachable();
+  } catch(e) {
+    assertTrue(/Object.isSealed called on non-object/.test(e));
+  }
+}
+
+// Test normal data properties.
+var obj = { x: 42, z: 'foobar' };
+var desc = Object.getOwnPropertyDescriptor(obj, 'x');
+assertTrue(desc.writable);
+assertTrue(desc.configurable);
+assertEquals(42, desc.value);
+
+desc = Object.getOwnPropertyDescriptor(obj, 'z');
+assertTrue(desc.writable);
+assertTrue(desc.configurable);
+assertEquals('foobar', desc.value);
+
+assertTrue(Object.isExtensible(obj));
+assertFalse(Object.isSealed(obj));
+
+Object.seal(obj);
+
+// Make sure we are no longer extensible.
+assertFalse(Object.isExtensible(obj));
+assertTrue(Object.isSealed(obj));
+
+// We should not be frozen, since we are still able to
+// update values.
+assertFalse(Object.isFrozen(obj));
+
+// We should not allow new properties to be added.
+try {
+   obj.foo = 42;
+   assertUnreachable();
+} catch(e) {
+  assertTrue(/object is not extensible/.test(e));
+}
+
+desc = Object.getOwnPropertyDescriptor(obj, 'x');
+assertTrue(desc.writable);
+assertFalse(desc.configurable);
+assertEquals(42, desc.value);
+
+desc = Object.getOwnPropertyDescriptor(obj, 'z');
+assertTrue(desc.writable);
+assertFalse(desc.configurable);
+assertEquals("foobar", desc.value);
+
+// Since writable is not affected by seal we should still be able to
+// update the values.
+obj.x = "43";
+assertEquals(43, obj.x);
+
+// Test on accessors.
+var obj2 = {};
+function get() { return 43; };
+function set() {};
+Object.defineProperty(obj2, 'x', { get: get, set: set, configurable: true });
+
+desc = Object.getOwnPropertyDescriptor(obj2, 'x');
+assertTrue(desc.configurable);
+assertEquals(undefined, desc.value);
+assertEquals(set, desc.set);
+assertEquals(get, desc.get);
+
+assertTrue(Object.isExtensible(obj2));
+assertFalse(Object.isSealed(obj2));
+Object.seal(obj2);
+
+// Since this is an accessor property the object is now effectively both
+// sealed and frozen (accessors has no writable attribute).
+assertTrue(Object.isFrozen(obj2));
+assertFalse(Object.isExtensible(obj2));
+assertTrue(Object.isSealed(obj2));
+
+desc = Object.getOwnPropertyDescriptor(obj2, 'x');
+assertFalse(desc.configurable);
+assertEquals(undefined, desc.value);
+assertEquals(set, desc.set);
+assertEquals(get, desc.get);
+
+try {
+  obj2.foo = 42;
+  assertUnreachable();
+} catch(e) {
+  assertTrue(/object is not extensible/.test(e));
+}
+
+
+// Test seal on arrays.
+var arr = new Array(42,43);
+
+desc = Object.getOwnPropertyDescriptor(arr, '0');
+assertTrue(desc.configurable);
+assertTrue(desc.writable);
+assertEquals(42, desc.value);
+
+desc = Object.getOwnPropertyDescriptor(arr, '1');
+assertTrue(desc.configurable);
+assertTrue(desc.writable);
+assertEquals(43, desc.value);
+
+assertTrue(Object.isExtensible(arr));
+assertFalse(Object.isSealed(arr));
+Object.seal(arr);
+assertTrue(Object.isSealed(arr));
+assertFalse(Object.isExtensible(arr));
+// Since the values in the array is still writable this object 
+// is not frozen.
+assertFalse(Object.isFrozen(arr));
+
+desc = Object.getOwnPropertyDescriptor(arr, '0');
+assertFalse(desc.configurable);
+assertTrue(desc.writable);
+assertEquals(42, desc.value);
+
+desc = Object.getOwnPropertyDescriptor(arr, '1');
+assertFalse(desc.configurable);
+assertTrue(desc.writable);
+assertEquals(43, desc.value);
+
+arr[0] = 'foo';
+
+// We should be able to overwrite the existing value.
+assertEquals('foo', arr[0]);
+
+
+// Test that isSealed returns the correct value even if configurable
+// has been set to false on all properties manually and the extensible
+// flag has also been set to false manually.
+var obj3 = { x: 42, y: 'foo' };
+
+assertFalse(Object.isFrozen(obj3));
+
+Object.defineProperty(obj3, 'x', {configurable: false, writable: true});
+Object.defineProperty(obj3, 'y', {configurable: false, writable: false});
+Object.preventExtensions(obj3);
+
+assertTrue(Object.isSealed(obj3));
+
+
+// Make sure that an object that has a configurable property
+// is not classified as sealed.
+var obj4 = {};
+Object.defineProperty(obj4, 'x', {configurable: true, writable: false});
+Object.defineProperty(obj4, 'y', {configurable: false, writable: false});
+Object.preventExtensions(obj4);
+
+assertFalse(Object.isSealed(obj4));