tests: add more tests for observer
tests: add more tests for observer

woltemade/framework,woltemade/framework,infamous/framework,SvitlanaShepitsena/shakou,Famous/framework,infamous/famous-framework,SvitlanaShepitsena/framework-1,jeremykenedy/framework,SvitlanaShepitsena/framework-1,KraigWalker/framework,infamous/famous-framework,SvitlanaShepitsena/framework,SvitlanaShepitsena/framework,KraigWalker/framework,SvitlanaShepitsena/remax-banner,ildarsamit/framework,SvitlanaShepitsena/remax-banner,tbossert/framework,colllin/famous-framework,colllin/famous-framework,infamous/framework,jeremykenedy/framework,Famous/framework,SvitlanaShepitsena/shakou,tbossert/framework,ildarsamit/framework