Are they really tests?
Yes and no. Basically the artist or musician gets tested already in private at home or at reharsals and then gets presented officially to La Zamba Playa to get "tested" officially, if the public agrees or goes crazy like in Roi David case the musician stays if not the musician is out, but this formula is recent Kapaya, Celeo, Bill and many of the old guard weren't tested, of course because they were with the original Wenge BCBG first. It is like the American Idol but with a single group doing it instead of a TV Show there are plenty of example that I can link
Check here
Then the Sarah Solo "test" Sarah solo brought back that enthusiasm Maison Mere had at the time.of Brigade where you can hear the whole African diaspora reacting to Maison Mere generique