As someone who knows how difficult it is Belarusian, Kazakh push elements in the Russian army, can tell you a fairy tale
Before selling the aircraft enters the temporary maintenance of the Russian Air Force, in order to test. After that, it is delivered to the buyer.
By the way, this may be the radars for 16 Su-30M2, which Russia built for a foreign customer, but he was unable to pay the order. Then, the state bought, and finish as the aircraft for the Russian Air Force. Other way, I do not know.