There have been news on the Russian web, that the new engine for the PAK-DA has begun trials on a stand. However the details reveal that the engine in question is a Soviet-era museum piece (literally, it was taken from an air and space museum of the Aerospace institute) called the NK-56 (D-4) where it's been for the last 30 years. They had to invite some retired personnel to get the engine running again.
ЧаÑтный руÑÑкий журнал - Ðазад в прошлое[ s2 h/QUOTE]
That seems to reference this article but which makes no mention of trials.
The image may be that of the old engine design but seems to imply a new engine for PAK DA. Nothing provided to support a comparison to the F135.
Russia tests engine for new bomber - 11/7/2014 - Flight Global
In June, state-owned media in Russia quoted Kuznetsov officials who announced the company had won a competition to develop the new engine for the PAK DA bomber...