Is it going to be broadcasted live?
No. You'll get the live blogs from Autosport and F1 Fanatic and the like, but no televised coverage.
It's often said that testing is meaningless to outsiders. Teams run their own programmes at their own pace, and they don't advertise what they are doing at any given time. Times, therefore, are not representative, as there is no context given to them; we do not know the conditions under which they are set, and achieving the team's outcomes is more important than pure pace.
Furthermore, testing runs for twelve hours a day, for three straight days. A single test will therefore take up thirty-six hours, or the equivalent of eighteen Grands Prix. In order to televise it, a broadcaster would need to send a full production and camera crew, which is over a hundred people, plus book satellite time to transmit the signal. It's expensive enough getting it in place for a single race, let alone a thirty-six hour block of continuous coverage. But assuming that they could afford it, what would they do once they got there? Like I said, we don't know the conditions under which times are set, and neither will commentators. So a broadcaster would spend hundreds of thousands - if not millions - of dollars broadcasting a single test where all they can do is guess at what is happening. And where is the audience going to be? Testing takes place during the working week.
It's simply not worth it. Broadcasting pre-season testing for the sake of a few die-hard fans has never been (and will never be) a commercially viable option. And the last thing that the teams will want is a camera crew buzzing around and filming their cars (particularly the diffuser) and broadcasting it for the rest of the paddock to see and imitate for the first race.