gecko-dev/browser/components/sessionstore/test/browser_687710.js

/* Any copyright is dedicated to the Public Domain.
   http://creativecommons.org/publicdomain/zero/1.0/ */

// Test that sessionrestore handles cycles in the shentry graph properly.
//
// These cycles shouldn't be there in the first place, but they cause hangs
// when they mysteriously appear (bug 687710).  Docshell code assumes this
// graph is a tree and tires to walk to the root.  But if there's a cycle,
// there is no root, and we loop forever.

var stateBackup = ss.getBrowserState();

var state = {windows:[{tabs:[{entries:[
  {
    docIdentifier: 1,
    url: "http://example.com",
    children: [
      {
        docIdentifier: 2,
        url: "http://example.com"
      }
    ]
  },
  {
    docIdentifier: 2,
    url: "http://example.com",
    children: [
      {
        docIdentifier: 1,
        url: "http://example.com"
      }
    ]
  }
]}]}]}

function test() {
  registerCleanupFunction(function () {
    ss.setBrowserState(stateBackup);
  });

  /* This test fails by hanging. */
  ss.setBrowserState(JSON.stringify(state));
  ok(true, "Didn't hang!");
}