The circumstances surrounding Niki Lauda's test with Ligier in 1977 still remain cloudy, but the run did happen as this picture attests.
In 1977, Lauda was in his last season with Ferrari and in talks with Bernie Ecclestone for a move to Brabham, for which the great Austrian would eventually drive the following year.
Lauda tested Ligier's JS7 at Zandvoort at the end of the season, and perhaps it was just a way of winding up Mr. E before entering serious negotiations...