The Tor Browser / file revision

 // # Regression tests for tor Bug #2950, Make Permissions Manager memory-only

 // Ensures that permissions.sqlite file in profile directory is not written to,

 // even when we write a value to Firefox's permissions database.

 // The requisite test() function.

 function test() {

 // Needed because of asynchronous part later in the test.

 waitForExplicitFinish();

 // Shortcut

 let Ci = Components.interfaces;

 // ## utility functions

 // __uri(spec)__.

 // Creates an nsIURI instance from a spec

 // (string address such as "http://torproject.org").

 let uri = spec => Services.io.newURI(spec, null, null);

 // __setPermission(spec, key, value)__.

 // Sets the site permission of type key to value, for the site located at address spec.

 let setPermission = (spec, key, value) => SitePermissions.set(uri(spec), key, value);

 // __getPermission(spec, key)__.

 // Reads the site permission value for permission type key, for the site

 // located at address spec.

 let getPermission = (spec, key) => SitePermissions.get(uri(spec), key);

 // __profileDirPath__.

 // The Firefox Profile directory. Expected location of various persistent files.

 let profileDirPath = Services.dirsvc.get("ProfD", Components.interfaces.nsIFile).path;

 // __fileInProfile(fileName)__.

 // Returns an nsIFile instance corresponding to a file in the Profile directory.

 let fileInProfile = fileName => FileUtils.File(profileDirPath + "/" + fileName);

 // ## Now let's run the test.

 let SITE = "http://torproject.org",

     KEY = "popup";

 let permissionsFile = fileInProfile("permissions.sqlite"),

                       lastModifiedTime = null,

                       newModifiedTime = null;

 if (permissionsFile.exists()) {

   lastModifiedTime = permissionsFile.lastModifiedTime;

 }

 // Read the original value of the permission.

 let originalValue = getPermission(SITE, KEY);

 // We need to delay by at least 1000 ms, because that's the granularity

 // of file time stamps, it seems.

 window.setTimeout(

   function () {

     // Set the permission to a new value.

     setPermission(SITE, KEY, (originalValue === 0) ? 1 : 0);

     // Now read back the permission value again.

     let newReadValue = getPermission(SITE, KEY);

     // Compare to confirm that the permission

     // value was successfully changed.

     isnot(newReadValue, originalValue, "Set a value in permissions db (perhaps in memory).");;

     // If file existed or now exists, get the current time stamp.

     if (permissionsFile.exists()) {

     	newModifiedTime = permissionsFile.lastModifiedTime;

     }

     // If file was created or modified since we began this test,

     // then permissions db is not memory only. Complain!

     is(lastModifiedTime, newModifiedTime, "Don't write to permissions.sqlite file on disk.");

     // We are done with the test.

     finish();

   }, 1100);

 } // test()