The Tor Browser / file revision

 function getTestPlugin(pluginName) {

   var ph = SpecialPowers.Cc["@mozilla.org/plugin/host;1"]

                                  .getService(SpecialPowers.Ci.nsIPluginHost);

   var tags = ph.getPluginTags();

   var name = pluginName || "Test Plug-in";

   for (var tag of tags) {

     if (tag.name == name) {

       return tag;

     }

   }

   ok(false, "Could not find plugin tag with plugin name '" + name + "'");

   return null;

 }

 // call this to set the test plugin(s) initially expected enabled state.

 // it will automatically be reset to it's previous value after the test

 // ends

 function setTestPluginEnabledState(newEnabledState, pluginName) {

   var plugin = getTestPlugin(pluginName);

   var oldEnabledState = plugin.enabledState;

   plugin.enabledState = newEnabledState;

   SimpleTest.registerCleanupFunction(function() {

     getTestPlugin(pluginName).enabledState = oldEnabledState;

   });

 }