On 16 December 2015 Pervy Kanal (Channel One) showed a discussion between the presidents of Russia and Belarus, Mr Vladimir Putin and Mr Alexander Lukashenko, during the latter's official visit to Russia. Mr Putin announced that migration amendments will be approved in the future that will exempt citizens from Belarus from Russian language tests (See the related GTA measures).
Federal Law No. 465-FZ of 30 December 2015 introduced the announced changes. 
Given that Russian is the primary--but not the only--language spoken in Belarus, the practical impact of this announcement may be limited.