[proxies] Implement [[Delete]].

test/mjsunit/harmony/proxies-delete-property.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
+
+
+var properties =
+    ["bla", "0", 1, Symbol(), {[Symbol.toPrimitive]() {return "a"}}];
+
+
+function TestForwarding(handler, myDelete, shouldThrow) {
+  var target = {};
+  var proxy = new Proxy(target, handler);
+
+  assertFalse(target.hasOwnProperty("doesnotexist"));
+  assertTrue(myDelete(proxy, "doesnotexist"));
+
+  for (p of properties) {
+    target[p] = 42;
+    assertTrue(myDelete(proxy, p));
+    assertFalse(target.hasOwnProperty(p));
+  }
+
+  for (p of properties) {
+    Object.defineProperty(target, p, {value: 42, configurable: false});
+    if (shouldThrow) {
+      assertThrows(() => myDelete(proxy, p), TypeError);
+    } else {
+      assertFalse(myDelete(proxy, p));
+    }
+    assertTrue(target.hasOwnProperty(p));
+  }
+};
+
+
+(function () {
+  // No trap.

[rossberg, 2015/11/25 17:53:35]

Nit: why not make that the function name (here and elsewhere)? Gives more useful
output when a test fails.

+
+  var handler = {};
+
+  TestForwarding(handler,
+      (o, p) => delete o[p], false);
+  TestForwarding(handler,
+      (o, p) => Reflect.deleteProperty(o, p), false);
+  TestForwarding(handler,
+      (o, p) => {"use strict"; return delete o[p]}, true);
+  TestForwarding(handler,
+      (o, p) => {"use strict"; return Reflect.deleteProperty(o, p)}, false);
+})();
+
+
+(function () {
+  // "Undefined" trap.
+
+  var handler = { deleteProperty: null };
+
+  TestForwarding(handler,
+      (o, p) => delete o[p], false);
+  TestForwarding(handler,
+      (o, p) => Reflect.deleteProperty(o, p), false);
+  TestForwarding(handler,
+      (o, p) => {"use strict"; return delete o[p]}, true);
+  TestForwarding(handler,
+      (o, p) => {"use strict"; return Reflect.deleteProperty(o, p)}, false);
+})();
+
+
+(function () {
+  // Invalid trap.
+
+  var target = {};
+  var handler = { deleteProperty: true };
+  var proxy = new Proxy(target, handler);
+
+  assertThrows(() => delete proxy[0], TypeError);
+  assertThrows(() => Reflect.deleteProperty(proxy, 0), TypeError);
+})();
+
+
+function TestTrappingTrueish(myDelete) {
+  var handler = { deleteProperty() {return 42} };
+  var target = {};
+  var proxy = new Proxy(target, handler);
+
+  // Trap returns trueish and target doesn't own property.
+  for (p of properties) {
+    assertTrue(myDelete(proxy, p));
+  }
+
+  // Trap returns trueish and target property is configurable.
+  for (p of properties) {
+    target[p] = 42;
+    assertTrue(myDelete(proxy, p));
+  }
+
+  // Trap returns trueish but target property is not configurable.
+  for (p of properties) {
+    Object.defineProperty(target, p, {value: 42, configurable: false});
+    assertThrows(() => myDelete(proxy, p), TypeError);
+  }
+};
+
+
+TestTrappingTrueish(
+    (o, p) => delete o[p]);
+TestTrappingTrueish(
+    (o, p) => Reflect.deleteProperty(o, p));
+TestTrappingTrueish(
+    (o, p) => {"use strict"; return delete o[p]});
+TestTrappingTrueish(
+    (o, p) => {"use strict"; return Reflect.deleteProperty(o, p)});
+
+
+function TestTrappingTrueish2(myDelete) {
+  var handler = {
+      deleteProperty(target, p) {
+          Object.defineProperty(target, p, {configurable: false});
+          return 42
+      }
+  };
+  var target = {};
+  var proxy = new Proxy(target, handler);
+
+  // Trap returns trueish but target property is not configurable.  In contrast
+  // to above, here the target property was configurable before the trap call.
+  for (p of properties) {
+    target[p] = 42;
+    assertThrows(() => myDelete(proxy, p), TypeError);
+  }
+};
+
+
+TestTrappingTrueish2(
+    (o, p) => delete o[p]);
+TestTrappingTrueish2(
+    (o, p) => Reflect.deleteProperty(o, p));
+TestTrappingTrueish2(
+    (o, p) => {"use strict"; return delete o[p]});
+TestTrappingTrueish2(
+    (o, p) => {"use strict"; return Reflect.deleteProperty(o, p)});
+
+
+function TestTrappingFalsish(myDelete, shouldThrow) {
+  var handler = { deleteProperty() {return ""} };
+  var target = {};
+  var proxy = new Proxy(target, handler);
+
+  var properties =
+      ["bla", "0", 1, Symbol(), {[Symbol.toPrimitive]() {return "a"}}];
+
+  // Trap returns falsish and target doesn't own property.
+  for (p of properties) {
+    if (shouldThrow) {
+      assertThrows(() => myDelete(proxy, p), TypeError);
+    } else {
+      assertFalse(myDelete(proxy, p));
+    }
+  }
+
+  // Trap returns falsish and target property is configurable.
+  for (p of properties) {
+    target[p] = 42;
+    if (shouldThrow) {
+      assertThrows(() => myDelete(proxy, p), TypeError);
+    } else {
+      assertFalse(myDelete(proxy, p));
+    }
+  }
+
+  // Trap returns falsish and target property is not configurable.
+  for (p of properties) {
+    Object.defineProperty(target, p, {value: 42, configurable: false});
+    if (shouldThrow) {
+      assertThrows(() => myDelete(proxy, p), TypeError);
+    } else {
+      assertFalse(myDelete(proxy, p));
+    }
+  }
+};
+
+
+TestTrappingFalsish(
+    (o, p) => delete o[p], false);
+TestTrappingFalsish(
+    (o, p) => Reflect.deleteProperty(o, p), false);
+TestTrappingFalsish(
+    (o, p) => {"use strict"; return delete o[p]}, true);
+TestTrappingFalsish(
+    (o, p) => {"use strict"; return Reflect.deleteProperty(o, p)}, false);