React with TypeScript and Testing App..!

Hi, devs,
I hope you are well. I trying to build a react app using TypeScript (ES6), React, and Redux. (I am NEW to write test cases for React app). And I would like to write tests case for each and every component (Automated unit/integration tests and static code checking and formatting)

here is the visual representation...

to write test cases for this application, what should have in mind!

for example what/which area you will cover to write a test case for an input-field and button components?

HappyCoding...:)