Initially you will undergo an online test which will have basic aptitude questions , programming questions(most likely very basic C questions) and a coding question which you can compile in any provided language you like(C,C++,python,java,C#.....)
Overall I would rate the online test as easy.
Once shortlisted you will have an interview in the nearby TCS campus.
The Interview process mainly have two parts 1)Technical and 2)HR.
In technical round you need to be prepared for basic oops concepts (loops, polymorphism,constructors ,destructors ...and some common interview programming questions).
What ever you write in your resume matters,as they might drill you on the skills that you declared in the resume.Try to avoid things that you are not confident in.
Then in the HR round, you need to cool and professional .You can expect questions like
...Are are willing to relocate? .... Where do you see yourself in 5 years?
