After the critical reception of his comedy The School for Wives, the French dramatist Molière wrote two one-act defenses of himself, The Critique of School for Wives and The Versailles Impromptu, the latter of which shows the playwright's own company attempting to rehearse a play for the king.

Molière, who originated the role of Arnolphe in The School for Wives, appears as himself, attempting to wrangle a troupe of actors into finishing the rehearsal on time. He is annoyed by a group of busybodies who constantly interrupt the rehearsal. The one-act comedy shows not just the rehearsal, but a play-within-the-play, in which characters discuss Molière's work, much as they had in The Critique of School for Wives. Silly characters speculate on who is being attacked in Molière's plays, while sensible ones take his comedies for being mere fictions.
To say all of this is a bit meta is perhaps an understatement. Molière had only recently married Armande Béjart, a young actress who had also appeared as Élise in The Critique of School for Wives. She appeared on stage as herself in The Versailles Impromptu, berating her husband (playing himself), who had also written the play. When he calls her names in exasperation, she remarks quite reasonably, "you wouldn’t have said that to me a year and a half ago" while he was still courting her. Though Molière wrote the play, he appears to give his wife the better argument.
Also appearing in the play is Mademoiselle Du Parc, an actress known more for her tragic portrayals than her comedy. When Molière tells her she is to play an affected young lady, she responds (presumably in an affected manner) "How could that be, when there’s nobody in the world less affected than I am?" I imagine that Du Parc was in on the joke, even if it was at her expense. Historically, she thrived as a part of Molière's company, though she later left (at the instigation of the tragic dramatist Jean Racine) to join a rival company at the Hôtel de Bourgogne.
The whole play is filled with in jokes. Most of the major actors in Molière's company make appearances as exaggerated versions of themselves, including Catherine de Brie, who originated the role of Agnès in The School for Wives, and Brécourt, who was the original Alain. We probably don't get half the jokes today, but it's still fun to read the play and envision what one of Molière's rehearsals was really like. I imagine they were quite dramatic, even if not quite as outrageous as the one in the play!