Achieve 100% test coverage

[jean-michelet]

Prerequisites

• [X] I have written a descriptive issue title
• [X] I have searched existing issues to ensure the issue has not already been raised

Issue

I'd like to try to increase test coverage, are you interested?

[Uzlopak]

sure, PRs are welcome ;)

[jean-michelet]

Let me know if there are other components that could benefit from increased code coverage. It's not always feasible but I can try, it helps me learn the internals.

Maybe these ones?

• https://github.com/fastify/fastify-reply-from/blob/master/.taprc
• https://github.com/fastify/under-pressure/blob/master/.taprc

[gurgunday]

Those would be great, yeah