Gelael, 20, will be at the first in-season test in Bahrain in April, in Hungary just before the August break and in Abu Dhabi after the championship ends in November.
Toro Rosso, preparing for Sunday's Australian season-opener in Melbourne, published the details on their Twitter feed along with a photograph of the driver having a seat fitting at the Faenza factory.
Gelael, who hopes to follow in the footsteps of Indonesia's first Formula One driver Rio Haryanto, will be competing in Formula Two -- the renamed GP2 feeder series -- this year after making his debut in 2016.
Haryanto is no longer in Formula One after losing his seat with now-defunct Manor.
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Gelael's father Ricardo runs the Kentucky Fried Chicken (KFC) franchise for Indonesia and was linked last year to a takeover of Manor.
(Reporting by Alan Baldwin in London, editing by Ken Ferris)
