Generator objects have [[Class]] === "Generator"

test/mjsunit/harmony/generators-objects.js

 // Copyright 2013 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.
 
-// Flags: --harmony-generators --harmony-scoping
+// Flags: --harmony-generators --harmony-scoping --allow-natives-syntax
 
 // Test instantations of generators.
 
 // Generators shouldn't allocate stack slots.  This test will abort in debug
 // mode if generators have stack slots.
 function TestContextAllocation() {
   function* g1(a, b, c) { yield 1; return [a, b, c]; }
   function* g2() { yield 1; return arguments; }
   function* g3() { yield 1; return this; }
   function* g4() { var x = 10; yield 1; return x; }
   // Temporary variable context allocation
   function* g5(l) { "use strict"; yield 1; for (let x in l) { yield x; } }
 
   g1();
   g2();
   g3();
   g4();
   g5(["foo"]);
 }
 TestContextAllocation();
 
 
 // Test the properties and prototype of a generator object.
 function TestGeneratorObject() {
   function* g() { yield 1; }
 
   var iter = g();
   assertSame(g.prototype, Object.getPrototypeOf(iter));
   assertTrue(iter instanceof g);
+  assertEquals("Generator", %ClassOf(iter));

[Michael Starzinger, 2013/04/17 12:52:19]

Could we also add a check for the ToString representation? The following should
do the trick AFAICT.

assertEquals("[object Generator]", Object.prototype.toString.call(iter));

Or alternatively ...

assertEquals("[object Generator]", String(iter));

[wingo, 2013/04/17 14:23:51]

Done.

   assertEquals([], Object.getOwnPropertyNames(iter));
   assertTrue(iter !== g());
 
   // g() is the same as new g().
   iter = new g();
   assertSame(g.prototype, Object.getPrototypeOf(iter));
   assertTrue(iter instanceof g);
+  assertEquals("Generator", %ClassOf(iter));

[Michael Starzinger, 2013/04/17 12:52:19]

Likewise.

[wingo, 2013/04/17 14:23:51]

Done.

   assertEquals([], Object.getOwnPropertyNames(iter));
   assertTrue(iter !== new g());
 }
 TestGeneratorObject();
+
+
+// Test the methods of generator objects.
+function TestGeneratorObjectMethods() {
+  function* g() { yield 1; }
+  var iter = g();
+
+  function TestNonGenerator(non_generator) {
+    non_generator.next = iter.next;

[Michael Starzinger, 2013/04/17 12:52:19]

For primitive values (i.e. the "1" value) this assignment will not cause
iter.next to be called below. Let's rewrite the check to use the following
instead ...

assertThrows("iter.send.call(non_generator)", TypeError);

Likewise for all four functions.

[wingo, 2013/04/17 14:23:51]

Done.

+    non_generator.send = iter.send;
+    non_generator.throw = iter.throw;
+    non_generator.close = iter.close;
+    assertThrows(function() { return non_generator.next(); }, TypeError);
+    assertThrows(function() { return non_generator.send(1); }, TypeError);
+    assertThrows(function() { return non_generator.throw(1); }, TypeError);
+    assertThrows(function() { return non_generator.close(); }, TypeError);
+  }
+
+  TestNonGenerator(1);
+  TestNonGenerator({});
+  TestNonGenerator(function(){});
+  TestNonGenerator(g);
+  TestNonGenerator(g.prototype);
+}
+TestGeneratorObjectMethods();