Flag files/patterns in my NPM package as dev-only? (e.g. tests directory)

I have a CLI tool that I have published on NPM, and it is installed by users either locally or globally.

I want to add some tests that are going to be of considerable size. Is there any way to signal to NPM that it should only pull down the tests when installing the package in dev mode and not in production mode?

I have found this answer that talks about .npmignore and about the files parameter in package.json. But I do want the tests to be installable when developing. So kind of like a hypothetical package.json devFiles parameter.