Education: BTech Tier-1 College
Years of Experience: 5.5 years
Current Company: Startup, laid off
Date of Interview : June 2023
R1: Machine coding
I recently interviewed at phonePe, during the preparation I had doubts regarding how machine coding round is conducted and how to prepare. So I will answer the question which I had.

How it is conducted ? : The coding round is conducted on codeSignal platform, You are given 2 hours to work on the problem statement. It is not a pair programming session, so no one will be present during test and there won't be any screen recording and you won't be asked to turn on camera.

Language choice? : The test won't have a specified language, you can choose any language of your choice. Prefer an object oriented language.

How to be prepared?: Since there are are limited number of questions which are asked in phonepe so make sure you have solved these question completely or partially (just the class structure). So that you can just copy paste stuff if familiar question is asked. Please make sure you undestand your solution too, asking to be prepared already because 2 hours time is less if you get stuck in silly mistake.

What to do during test?: Please try to attempt question in your code editor, because in editor it's easy to see code side by side and scrolling time is saved. Usually you will write your code in single file so scrolling and reading gets hard in code signal. Write in single file(but in object oriented way) so that once you are done you can just copy and paste single file. While writing in editor complie code side by side in codeSignal too, to avoid the surprises at the end. You don't have to use any DB so everything should be in memory.
Please write test cases too (not unit tests), even though if you dont have time to write the excecutable code for it. If you are not able to implement something make sure to leave a comment, i.e. write a class and comment this should ideally be an interface.

What to expect later? : Later a review session will be conducted for 30 mins in 1-2 days, here you can expect questions like explain the basic structure, how would you extend for any usecase, how to make it production ready, what kind of DB, will there be different services for different components in production. Here you can mention design pattern used.

In short if you prepare well you can clear this round, I was not able to get such descriptive information about machine round, so if you think it's helpful please upvote. Let me know if you have anyother questions in comments.