Approximately every month are provided test days for different teams that will get a total of three test days each. Today and tomorrow it's the team's turn Red Bull.
It means they will have to Max Verstappen in Sergio Perez to stay in Barcelona for a while. Because today and tomorrow it will be Red Bull tested new ones Pirelli's tires. In addition Red Bulla, the two teams will stay in Barcelona as well AlpineF1 in Alfa Romeo. In doing so, Alfa Romeo will test both days, and the French team AlpineF1 only today.
Because The French new tires have been tested before, as has the team Ferrari in Mercedes. The latter will get another two weeks one chance for the test, but then with new rain tires. Interestingly, so far the test with the new rain tires has only been planned at Ferrari, Mercedes in AlpineF1. In addition, for the team Williams no test days are planned.