Formula 2 driver Sean Gelael has been handed four FP1 outings by the Toro Rosso team, which will come in Singapore, Malaysia, USA and Mexico.
The Indonesian, who is currently 20th in the F2 standings driving for Arden, has previously driven the STR12 during post-race testing in Bahrain and Hungary earlier this season.
"During the tests in Bahrain and Budapest Sean performed very well, helping the team in a very professional way, with a mature approach to the complex task of providing engineers with useful feedback," said team boss Franz Tost.
"Everyone within the team was impressed by his performance, his technical understanding and his commitment."
Toro Rosso have yet to confirm which full-time driver, Carlos Sainz or Daniil Kvyat, will be replaced during the sessions.
Gelael added: "I will use the opportunity to absorb like a sponge everything I can and learn as much as possible.
"I hope I can do a good job for Scuderia Toro Rosso and provide the team with good data from these important first sessions."
