The Tor Browser / file revision

 var DEBUG = false;

 var clientID = "javascript";

 var key = "theme:button";

 var nsICache = Components.interfaces.nsICache;

 function getCacheService()

 {

     var nsCacheService = Components.classes["@mozilla.org/network/cache-service;1"];

     var service = nsCacheService.getService(Components.interfaces.nsICacheService);

     return service;

 }

 function createCacheSession(clientID, storagePolicy, streamable)

 {

     var service = getCacheService();

     var session = service.createSession(clientID, storagePolicy, streamable);

     return session;

 }

 function openCacheEntry(mode)

 {

     var session = createCacheSession(clientID, nsICache.STORE_ON_DISK, true);

     var entry = session.openCacheEntry(key, mode);

     return entry;

 }

 function wrapInputStream(input)

 {

     var nsIScriptableInputStream = Components.interfaces.nsIScriptableInputStream;

     var factory = Components.classes["@mozilla.org/scriptableinputstream;1"];

     var wrapper = factory.createInstance(nsIScriptableInputStream);

     wrapper.init(input);

     return wrapper;

 }

 function test()

 {

     var outputEntry = openCacheEntry(nsICache.ACCESS_WRITE);

     var output = outputEntry.transport.openOutputStream(0, -1, 0);

     if (output.write("foo", 3) == 3)

         print("disk cache write works!");

     else

         print("disk cache write broken!");

     // store some metadata.

     outputEntry.setMetaDataElement("size", "3");

     output.close();

     outputEntry.markValid();

     outputEntry.close();

     var inputEntry = openCacheEntry(nsICache.ACCESS_READ);

     var input = wrapInputStream(inputEntry.transport.openInputStream(0, -1, 0));

     if (input.read(input.available()) == "foo")

         print("disk cache read works!");

     else

         print("disk cache read broken!");

     if (inputEntry.getMetaDataElement("size") == "3")

         print("disk cache metadata works!");

     else

         print("disk cache metadata broken!");

     input.close();

     inputEntry.close();

 }

 function doom()

 {

     var doomedEntry = openCacheEntry(nsICache.ACCESS_READ_WRITE);

     doomedEntry.doom();

     doomedEntry.close();

 }

 if (DEBUG) {

     getCacheService();

     print("cache service loaded.");

 } else {

     print("running disk cache test.");

     test();

     print("disk cache test complete.");

 }