Back in the day, the only way you got into a major motion picture if you were Black was to:

1. Play maid or chauffeur

2. Be in an "All-Negro" production

3. Sing and/or dance in the middle of a "standard" production

Lena Horne was the undisputed champion of the 3rd category in the 1940s.  She was cast in a dozen or so movies in which she had no role whatsoever except to appear in some disconnected scene and sing/dance for 2 or 3 minutes, then disappear for the rest of the movie.

Here she is, in one of those movies ("Broadway Rhythm", 1944, MGM), singing "Brazilian Boogie".

Included here for it's Latin flair (Hollywood Style, of course).