test_browsing_context_structured_clone.js

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"use strict";

add_task(async function test_BrowsingContext_structured_clone() {

  let browser = Services.appShell.createWindowlessBrowser(false);

  let frame = browser.document.createElement("iframe");

  await new Promise(r => {

    frame.onload = () => r();

    browser.document.body.appendChild(frame);

});

  let { browsingContext } = frame;

  let sch = new StructuredCloneHolder("debug name", "<anonymized> debug name", {

    browsingContext,

});

  let deserialize = () => sch.deserialize({}, true);

  // Check that decoding a live browsing context produces the correct

  // object.

  equal(

    deserialize().browsingContext,

    browsingContext,

    "Got correct browsing context from StructuredClone deserialize"

);

  // Check that decoding a second time still succeeds.

  equal(

    deserialize().browsingContext,

    browsingContext,

    "Got correct browsing context from second StructuredClone deserialize"

);

  // Destroy the browsing context and make sure that the decode fails

  // with a DataCloneError.

//

  // Making sure the BrowsingContext is actually destroyed by the time

  // we do the second decode is a bit tricky. We obviously have clear

  // our local references to it, and give the GC a chance to reap them.

  // And we also, of course, have to destroy the frame that it belongs

  // to, or its frame loader and window global would hold it alive.

//

  // Beyond that, we don't *have* to reload or destroy the parent

  // document, but we do anyway just to be safe.

//

  frame.remove();

  frame = null;

  browsingContext = null;

  browser.document.location.reload();

  browser.close();

  // We will schedule a precise GC and do both GC and CC a few times, to make

  // sure we have completely destroyed the WindowGlobal actors (which keep

  // references to their BrowsingContexts) in order

  // to allow their (now snow-white) references to be collected.

  await schedulePreciseGCAndForceCC(3);

  // OK. We can be fairly confident that the BrowsingContext object

  // stored in our structured clone data has been destroyed. Make sure

  // that attempting to decode it again leads to the appropriate error.

  Assert.throws(

    deserialize,

    e => e.name === "DataCloneError",

    "Should get a DataCloneError when trying to decode a dead BrowsingContext"

);

});