Is a novel defined by its length or by a certain approach? According to Wikipedia, Snoopy’s It was a Dark and Stormy Night is a novel because of certain perspective on life, an attempt to present a “totality of life.” It qualifies as metafiction, because it exposes conventions of the novel, namely an epic treatment of life.
From the Wikipedia article on the novel: Snoopy’s novel It Was A Dark And Stormy Night which followed the 1965 cartoon in 1971 proves that the requirement of length is actually secondary to the requirement of a certain perspective on life – which Snoopy can easily offer in 214 words:
The text is shorter than most short stories yet definitely a novel thanks to the author’s attempts to risk what Lukács had seen as the “Great epic’s” potential to “give form to the extensive totality of life.” The requirement of length has been traditionally connected with the notion that epic length performances try to cope with the “totality of life”. The novella is by contrast focused on a point, the short story on a situation whose full dimensions the reader has to grasp in a complex process of interpretation.