Update ObjectToString to Harmony-draft algorithm

test/mjsunit/es6/object-tostring.js

+// Copyright 2014 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-tostring
+
+var global = this;
+
+// TODO(dslomov, caitp): remove the following simple tests (dupe from
+// class-of-builtins) when shipping.

[Dmitry Lomov (no reviews), 2014/10/18 21:24:19]

I wouldn't even add this TODO here, extra tests are fine

+var funs = {
+  Object:   [ Object ],
+  Function: [ Function ],
+  Array:    [ Array ],
+  String:   [ String ],
+  Boolean:  [ Boolean ],
+  Number:   [ Number ],
+  Date:     [ Date ],
+  RegExp:   [ RegExp ],
+  Error:    [ Error, TypeError, RangeError, SyntaxError, ReferenceError, EvalError, URIError ]

[Dmitry Lomov (no reviews), 2014/10/18 21:24:19]

Nit: 80 line string

[Dmitry Lomov (no reviews), 2014/10/18 21:27:14]

s/line/column/

+}
+for (f in funs) {
+  for (i in funs[f]) {
+    assertEquals("[object " + f + "]",
+                 Object.prototype.toString.call(new funs[f][i]),
+                 funs[f][i]);
+    assertEquals("[object Function]",
+                 Object.prototype.toString.call(funs[f][i]),
+                 funs[f][i]);
+  }
+}
+
+function testToStringTag(className) {
+  // Using builtin toStringTags
+  var obj = {};
+  obj[Symbol.toStringTag] = className;
+  assertEquals("[object ~" + className + "]",
+               Object.prototype.toString.call(obj));
+
+  // Getter throws
+  obj = {};
+  Object.defineProperty(obj, Symbol.toStringTag, {
+    get: function() { throw className; }
+  });
+  assertThrows(function() {
+    Object.prototype.toString.call(obj);
+  }, className);
+
+  // Getter does not throw
+  obj = {};
+  Object.defineProperty(obj, Symbol.toStringTag, {
+    get: function() { return className; }
+  });
+  assertEquals("[object ~" + className + "]",
+               Object.prototype.toString.call(obj));
+
+  // Custom, non-builtin toStringTags
+  obj = {};
+  obj[Symbol.toStringTag] = "X" + className;
+  assertEquals("[object X" + className + "]",
+               Object.prototype.toString.call(obj));
+
+  // With getter
+  obj = {};
+  Object.defineProperty(obj, Symbol.toStringTag, {
+    get: function() { return "X" + className; }
+  });
+  assertEquals("[object X" + className + "]",
+               Object.prototype.toString.call(obj));
+
+  // Undefined toStringTag should return [object className]
+  var obj = className === "Arguments" ?

[Dmitry Lomov (no reviews), 2014/10/18 21:24:19]

Formatting is off

+            (function() { return arguments; })() :
+  new global[className];
+  obj[Symbol.toStringTag] = undefined;
+  assertEquals("[object " + className + "]",
+               Object.prototype.toString.call(obj));
+
+  // With getter
+  var obj = className === "Arguments" ?

[Dmitry Lomov (no reviews), 2014/10/18 21:24:19]

Formatting is off

+            (function() { return arguments; })() :
+  new global[className];
+  Object.defineProperty(obj, Symbol.toStringTag, {
+    get: function() { return undefined; }
+  });
+  assertEquals("[object " + className + "]",
+               Object.prototype.toString.call(obj));
+}
+
+[
+  "Arguments",
+  "Array",
+  "Boolean",
+  "Date",
+  "Error",
+  "Function",
+  "Number",
+  "RegExp",
+  "String"
+].forEach(testToStringTag);
+
+function testToStringTagNonString(value) {
+  var obj = {};
+  obj[Symbol.toStringTag] = value;
+  assertEquals("[object ???]", Object.prototype.toString.call(obj));
+
+  // With getter
+  obj = {};
+  Object.defineProperty(obj, Symbol.toStringTag, {
+    get: function() { return value; }
+  });
+  assertEquals("[object ???]", Object.prototype.toString.call(obj));
+}
+
+[
+  null,
+  function() {},
+  [],
+  {},
+  /regexp/,
+  42,
+  Symbol("sym"),
+  new Date(),
+  (function() { return arguments; })(),
+  true,
+  new Error("oops"),
+  new String("str")
+].forEach(testToStringTagNonString);

[Dmitry Lomov (no reviews), 2014/10/18 21:24:19]

Also add a test that check properties of Object.prototype.toString (should be
writeable, non-enumerable, configurable)