jest-compare-reporter

What this is

A simple jest reporter that will output previous and current test coverage results. BYO git hooks to police yourself and make sure your code coverage doesn't fall.

How to use it

1. npm install jest-compare-reporter
2. Add the reporter to your jest config (ex: https://jestjs.io/docs/configuration#coveragereporters-arraystring--string-options)
   2a. Alternatively you can use it from the CLI (ex: https://jestjs.io/docs/cli#--reporters)
3. This outputs a file that compares the coverage between the previous run and the current run.
4. Use the file however you'd like. I made it with the intention of being used with git hooks.