Prepackage Checks

Looks for references to files in package.json and complains if they don't exist.

Usage

Adding this package to your devDependencies will give you access to a prepackage-checks binary, which you can call from any npm script.

Despite the name, it's sensible to run this test routinely rather than only immediately before publishing.

Motivation

I published an NPM package, but it didn't work because the files I'd declared in my package.json didn't actually exist. This tool is an attempt to avoid making that mistake again, although I'm sure that I'll instead make exciting new mistakes.

Implementation

I use Jest for general testing, and this package started life as a set of Jest tests in one of my library projects. Having copied it a couple of times, the time seemed ripe to extract the tooling into a separate package for easier reuse.

Jest has no "proper" API, but it does expose its CLI directly as a library. Rather than rewrite the tests to run without Jest, we use Jest's CLI API to run the tests directly from the package. This lets us avoid picking up any Jest configuration from the calling package; we are entirely self-contained.

There is no requirement for the package being validated to use Jest for its tests, or indeed for it to depend on Jest in any way apart from indirectly via this package.