I've used this library professionally in many projects. It is a necessity to use this in the long run and a number of people are working on the same code because we don't want someone to accidentally push some changes to fix something at one place and that can cause bugs somewhere else. It comes with all the necessary hooks, such as beforeEach, afterEach, etc. Well documented with examples
I prefer Mocha and Chai over this just because I found those packages first. Learning new syntax for writing test cases seems like an overhead, even though its fairly easy and comes with pretty much all the hooks that are there in Mocha.
I've used this package in a side-project. It offers great customisability for integrating calendar in the react application. One major issue that didn't let me to use it in my company project was that it doesn't support old browsers (even though those browsers were deprecated by their makers, but still). Well documented.
This is a great package to have our way with the contacts list. One can read existing contacts, update them, and even add new contacts using this library. We need to ask for appropriate permissions such as read/write contacts depending on the application scope. Well documented usage.
This package is extremely useful, and a must have during development phase of the application. Whenever there are only java script changes, we can simply run the code push command through CLI, and QA team will receive receive notifications to update the app directly, just as it would happen with an app installed from play store or app store. It is a little tricky to setup for newbies.
It used to be a part of official react native packages, but now has moved to community packages. It has neat and clean documentation with usage examples. If someone is new to RN, they can simply use this library to save and query data from an unsecured app specific database instead of learning how to do the same using redux state container.
I've used this library for request payload validation in a Hapijs project professionally. It has one word functions for checking the variable type, whether its a string or date, or whether null is allowed, and if the condition is not satisfied it throws the error which is handled by the error handler. We can also provide it with custom variable names for error or an error message itself. It is very well documented.
This is a must have for every project specially when we're working in a group and everyone has a different way of coding, it helps in maintaining code handwriting 😉. Neat documentation with well explained examples.