third_party/WebKit/LayoutTests/fast/harness/internals-observe-gc.html

   1 <!DOCTYPE html>
   2 <script src="../../resources/js-test.js"></script>
   3 <body>
   4 <script>
   5 description('Tests that the window.internals.observeGC hook works.');
   6
   7 shouldBe('typeof window.internals.observeGC', '"function"',
   8          'this test requires window.internals');
   9
  10 // "Generic Kid's Movie III": ... where nobody dies.
  11
  12 var valueA = {};
  13 observationA = internals.observeGC(valueA);
  14 gc();
  15 shouldBeFalse('observationA.wasCollected');
  16 // value ineligible for GC should not be flagged as collected
  17 valueA = null;
  18 observationA = null;
  19
  20 // "Romeo and GCuliet": Romeo JavaScript finds G.uliet C.apulet and dies.
  21
  22 var valueB = {};
  23 observationB = internals.observeGC(valueB);
  24 valueB = null;
  25 gc();
  26 shouldBeTrue('observationB.wasCollected');
  27 // value eligible for GC should be flagged as collected
  28 observationB = null;
  29
  30 // "One DOM Tree Hill": A family struggles with the loss of
  31 // innocence. And a DOM node.
  32
  33 var valueC = document.createElement('div');
  34 observationC = internals.observeGC(valueC);
  35 valueC = null;
  36 gc();
  37 shouldBeTrue('observationC.wasCollected');
  38 // DOM node eligible for GC should be flagged as collected
  39 observationC = null;
  40
  41 // Now, movies that failed:
  42
  43 shouldThrow('internals.observeGC(undefined)', '"TypeError: value to observe is null or undefined"');
  44 shouldThrow('internals.observeGC(null)', '"TypeError: value to observe is null or undefined"');
  45
  46 // Try to create objects and observers that will die at once
  47
  48 var valueD = {};
  49 var observerD = internals.observeGC(valueD);
  50 valueD.observer = observerD;
  51 observerD.observed = valueD;
  52 valueD = observerD = null;
  53 gc();
  54 testPassed('did not crash');
  55
  56 var successfullyParsed = true;
  57 </script>