Britain's Oliver Rowland has been named as Williams' official young driver for 2018.
Rowland, who was Renault's development driver last year, will take part in the official F1 young driver test in Spain in May and do simulator work.
The 25-year-old, who raced in Formula 2 last year, will also compete in the World Endurance Championship.
Deputy team principal Claire Williams described Rowland as "a talented and highly regarded young driver".
Rowland said he was "immensely proud" to join Williams, who also have former F1 driver Robert Kubica as their official reserve driver, supporting race drivers Sergey Sirotkin and Lance Stroll.