The Swiss team said they would not participate due to not having any updates to trial, and also because they do not have a young driver who would 'fulfill the requirements'.
Each team must allocate at least two of the four in-season test days this year to training young drivers.
The Spanish test, which runs on May 17-18, is the first of two in-season tests this year, with the second coming after the 2016 Formula 1 British Grand Prix at Silverstone on July 12-13.
The rest of the teams are yet to announce their line-ups for the Spanish test.
