Hmm, I've never heard it used outside of RSpec, but I don't have much exposure to using test doubles outside of an RSpec context.

Anyhow, in #444 the term we decided on for the new config option was "partial double", so we should be consistent here.  If we want to change how we refer to the concept, we can, but that is a bigger issue that we should address in a separate PR if we do address it.  For now, being consistent with that naming is best, I think.