The German is a strong contender for the vacant seat alongside Paul di Resta, with Jules Bianchi also in the running.
The team is not expected to make any announcements about its second driver this week, but confirmed its plans for the Barcelona test would be revealed on Monday.
"Adrian has had a seat fitting with the team this week," a spokesperson told AUTOSPORT.
"At this stage, the test driving schedule for the Barcelona test is not finalised but there is a possibility Adrian could be involved.
"The driving schedule will be communicated on Monday next week."