v8/test/mjsunit/es6/generators-objects.js

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// Flags: --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));
  assertEquals("[object Generator]", String(iter));
  assertEquals([], Object.getOwnPropertyNames(iter));
  assertTrue(iter !== g());
  assertEquals("[object Generator]", Object.prototype.toString.call(iter));
  var gf = iter.__proto__.constructor;
  assertEquals("[object GeneratorFunction]", Object.prototype.toString.call(gf));

  // generators are not constructable.
  assertThrows(()=>new g());
}
TestGeneratorObject();


// Test the methods of generator objects.
function TestGeneratorObjectMethods() {
  function* g() { yield 1; }
  var iter = g();

  function TestNonGenerator(non_generator) {
    assertThrows(function() { iter.next.call(non_generator); }, TypeError);
    assertThrows(function() { iter.next.call(non_generator, 1); }, TypeError);
    assertThrows(function() { iter.throw.call(non_generator, 1); }, TypeError);
  }

  TestNonGenerator(1);
  TestNonGenerator({});
  TestNonGenerator(function(){});
  TestNonGenerator(g);
  TestNonGenerator(g.prototype);
}
TestGeneratorObjectMethods();