I just learnt from my mentor that there is a way to create a shell script to run the whole gamut of testing without going thru Postman, as it is really a chore to test the end point one after another.
But, I wasn't told how to do it.
As such, I hope I can get some hints how to do it cos the only shell script I ever learnt is the execute in a docker where you can indicate where is your file and then follows by what you want the script to do next, such as change drive, bringing in the various docker images etc etc.
But, in this new task that I hope to know, I have no idea how to begin...
Hope you guys can point me to some good resources to gain knowledge in this and how to write a shell script.
You're talking about quite a few different concepts here. Initially you asked about a method in which you can automatically run a bunch of test cases, for which Junit is a good choice, and now you're talking about in memory databases, mocking, Spring Boot, and JPA.
My best recommendation at this point is this: Do one thing at a time.