[proxies] Implement [[Set]].

test/mjsunit/harmony/proxies-set.js

+// Copyright 2015 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-proxies --harmony-reflect
+
+
+// TODO(neis): There is so much more we could test, for instance:
+// - Test with non-trivial receiver argument.
+// - Test with function proxies as setters/getters.
+// - Test with proxies in the prototype chain.
+// - Check that non-object receiver is passed to proxy in prototype
+//   chain.
+
+
+function sloppyDefaultSet(o, p, v) { return o[p] = v }
+function sloppyReflectSet(o, p, v) { return Reflect.set(o, p, v) }
+function strictDefaultSet(o, p, v) { "use strict"; return o[p] = v }
+function strictReflectSet(o, p, v) { "use strict"; return Reflect.set(o, p, v) }
+
+sloppyDefaultSet.shouldThrow = false;
+sloppyReflectSet.shouldThrow = false;
+strictDefaultSet.shouldThrow = true;
+strictReflectSet.shouldThrow = false;
+
+sloppyDefaultSet.returnsBool = false;
+sloppyReflectSet.returnsBool = true;
+strictDefaultSet.returnsBool = false;
+strictReflectSet.returnsBool = true;
+
+
+function assertTrueIf(flag, x) { if (flag) assertTrue(x) }
+function assertFalseIf(flag, x) { if (flag) assertFalse(x) }
+function assertSetFails(mySet, o, p, v) {
+  if (mySet.shouldThrow) {
+    assertThrows(() => mySet(o, p, v), TypeError);
+  } else {
+    assertFalseIf(mySet.returnsBool, mySet(o, p, v));
+  }
+}
+
+
+function dataDescriptor(x) {
+  return {value: x, writable: true, enumerable: true, configurable: true};
+}
+
+
+function toKey(x) {
+  if (typeof x === "symbol") return x;
+  return String(x);
+}
+
+
+var properties =
+    ["bla", "0", 1, Symbol(), {[Symbol.toPrimitive]() {return "a"}}];
+
+
+function TestForwarding(handler, mySet) {
+  assertTrue(undefined == handler.set);
+  assertTrue(undefined == handler.getOwnPropertyDescriptor);
+  assertTrue(undefined == handler.defineProperty);
+
+  var target = {};
+  var proxy = new Proxy(target, handler);
+
+  // Property does not exist on target.
+  for (var p of properties) {
+    assertTrueIf(mySet.returnsBool, mySet(proxy, p, 42));
+    assertSame(42, target[p]);
+  }
+
+  // Property exists as writable data on target.
+  for (var p of properties) {
+    assertTrueIf(mySet.returnsBool, mySet(proxy, p, 0));
+    assertSame(0, target[p]);
+  }
+
+  // Property exists as non-writable data on target.
+  for (var p of properties) {
+    Object.defineProperty(target, p,
+        {value: 42, configurable: true, writable: false});
+    assertSetFails(mySet, proxy, p, 42);
+    assertSetFails(mySet, proxy, p, 0);
+    assertEquals(42, target[p]);
+  }
+};
+
+
+(function () {
+  // No trap.
+
+  var handler = {};
+
+  TestForwarding(handler, sloppyDefaultSet);
+  TestForwarding(handler, sloppyReflectSet);
+  TestForwarding(handler, strictDefaultSet);
+  TestForwarding(handler, strictReflectSet);
+})();
+
+
+(function () {
+  // "Undefined" trap.
+
+  var handler = { set: null };
+
+  TestForwarding(handler, sloppyDefaultSet);
+  TestForwarding(handler, sloppyReflectSet);
+  TestForwarding(handler, strictDefaultSet);
+  TestForwarding(handler, strictReflectSet);
+})();
+
+
+function TestForwarding2(mySet) {
+  // Check that setting on a proxy without "set" trap correctly triggers its
+  // "getOwnProperty" trap and its "defineProperty" trap.
+
+  var target = {};
+  var handler = {};
+  var observations = [];
+  var proxy = new Proxy(target, handler);
+
+  handler.getOwnPropertyDescriptor = function() {
+      observations.push(arguments);
+      return Reflect.getOwnPropertyDescriptor(...arguments);
+  }
+
+  handler.defineProperty = function() {
+      observations.push(arguments);
+      return Reflect.defineProperty(...arguments);
+  }
+
+  for (var p of properties) {
+    Reflect.set(proxy, p, 42);
+    assertEquals(2, observations.length)
+    assertArrayEquals([target, toKey(p)], observations[0]);
+    assertArrayEquals([target, toKey(p), dataDescriptor(42)], observations[1]);
+    observations = [];
+
+    Reflect.set(proxy, p, 42);
+    assertEquals(2, observations.length)
+    assertArrayEquals([target, toKey(p)], observations[0]);
+    assertArrayEquals([target, toKey(p), {value: 42}], observations[1]);
+    observations = [];
+  }
+}
+
+
+TestForwarding2(sloppyDefaultSet);
+TestForwarding2(sloppyReflectSet);
+TestForwarding2(strictDefaultSet);
+TestForwarding2(strictReflectSet);
+
+
+function TestInvalidTrap(proxy, mySet) {
+  for (var p of properties) {
+    assertThrows(() => mySet(proxy, p, 42), TypeError);
+  }
+}
+
+
+(function () {
+  var target = {};
+  var handler = { set: true };
+  var proxy = new Proxy(target, handler);
+
+  TestInvalidTrap(proxy, sloppyDefaultSet);
+  TestInvalidTrap(proxy, sloppyReflectSet);
+  TestInvalidTrap(proxy, strictDefaultSet);
+  TestInvalidTrap(proxy, strictReflectSet);
+})();
+
+
+function TestTrappingFalsish(mySet) {
+  var target = {};
+  var handler = { set() {return ""} };
+  var proxy = new Proxy(target, handler);
+
+  for (var p of properties) {
+    assertSetFails(mySet, proxy, p, 42);
+  }
+}
+
+
+TestTrappingFalsish(sloppyDefaultSet);
+TestTrappingFalsish(sloppyReflectSet);
+TestTrappingFalsish(strictDefaultSet);
+TestTrappingFalsish(strictReflectSet);
+
+
+function TestTrappingTrueish(mySet) {
+  var target = {};
+  var handler = { set() {return 42} };
+  var proxy = new Proxy(target, handler);
+
+  // Trap returns trueish and property does not exist in target.
+  for (var p of properties) {
+    assertTrueIf(mySet.returnsBool, mySet(proxy, p, 0));
+  }
+
+  // Trap returns trueish and target property is configurable or writable.
+  for (var p of properties) {
+    Object.defineProperty(target, p, {configurable: true, writable: true});
+    assertTrueIf(mySet.returnsBool, mySet(proxy, p, 0));
+    Object.defineProperty(target, p, {configurable: true, writable: false});
+    assertTrueIf(mySet.returnsBool, mySet(proxy, p, 0));
+    Object.defineProperty(target, p, {configurable: false, writable: true});
+    assertTrueIf(mySet.returnsBool, mySet(proxy, p, 0));
+  }
+}
+
+
+TestTrappingTrueish(sloppyDefaultSet);
+TestTrappingTrueish(sloppyReflectSet);
+TestTrappingTrueish(strictDefaultSet);
+TestTrappingTrueish(strictReflectSet);
+
+
+function TestTrappingTrueish2(mySet) {
+  var target = {};
+  var handler = { set() {return 42} };
+  var proxy = new Proxy(target, handler);
+
+  // Trap returns trueish but target property is frozen.
+  for (var p of properties) {
+    Object.defineProperty(target, p, {
+        configurable: false, writable: false, value: 0
+    });
+    assertThrows(() => mySet(proxy, p, 666), TypeError);  // New value.
+    assertTrueIf(mySet.returnsBool, mySet(proxy, p, 0));  // Old value.
+  }
+};
+
+
+TestTrappingTrueish2(sloppyDefaultSet);
+TestTrappingTrueish2(sloppyReflectSet);
+TestTrappingTrueish2(strictDefaultSet);
+TestTrappingTrueish2(strictReflectSet);