Latifi said a large part of his role would be simulator driving and helping development of the new Williams car
Canadian Nicholas Latifi will be reserve driver for Williams in 2019.
The 23-year-old, a race-winner in Formula 2, moves from Force India, where he was development driver and took part in some practice sessions in 2018.
Fernando Alonso raced the Indianapolis 500 in 2017 but was forced out in the closing stages by engine failure
Fernando Alonso will use a Chevrolet engine for his bid to win the Indianapolis 500 next year, his McLaren team have confirmed.
The announcement was a formality because Honda, the only other engine manufacturer in Indycar, had refused to supply an engine for Alonso's car.
Lance Stroll (right) with Esteban Ocon, who he will be replacing as driver in the Force India team for the 2019 Formula 1 season
Canadian driver Lance Stroll is to race for Force India in 2019.
His move from Williams, for whom he made his debut in 2017, has been Formula 1's worst-kept secret since his father bought Force India in August.
Albon said it was an "incredible opportunity" to race for Toro Rosso
Red Bull junior team Toro Rosso have signed Alexander Albon to compete their line-up for 2019.
It means there will be four drivers of British origin on the grid next year.
Hamilton said after 83rd career pole: "I'm so grateful for the mechanics who put this [car] together for me."
Lewis Hamilton won the Abu Dhabi Grand Prix to end the season in which he clinched his fifth world championship on a high.
It was the 11th victory of the year for Hamilton, who dominated the race with a controlled drive.
