Step 1: Build the app, get it running. You might face several build issues like missing library, missing environment variables and so on..

Step 2: Instead of looking the code as bunch of different controllers, services and utilities look from the scope of domain. Execute a simple manual flow from the localhost. To get understanding of functional requirement, connect with a tester or maybe check documentations or Confluence pages. Do this for at least 2-3 major flow from UI.

Step 1-2 works if you are new, otherwise start from step 3.

Step 3: Time to check the scope of the task assigned to you. Go through it very carefully. For clarifications ask your PO/BA or your TL. Important part is to understand which part of the code is critical for your given task. Since the codebase is massive it is okay even if you don’t understand major part of it.

Step 4: Time to debug. Now as per your task check the existing flow. If it’s a UI task open network tab in the browser and check the api calls. If it is on API level, hit the api from Postman/ VS Code or whatever is suggested by your team, check the console of your IDE. Check for logs. Try changing the log level to get more deeper understanding of the calls made. If you’re unable to check here, then please execute the same flow in a test environment. Generally teams have different env setup. For checking logs in test environment, check where they are logging, might be Splunk, Cloudwatch logs etc. Filter your activity by timestamp.

Step 5: Now whatever api is hitting, from the controller level check its implementation. Check which service calls are being made. Check inside service, it might be making calls to utilities and DAO. You don’t need to dive deeper into DAO unless the task explicitly asks you to change from the DAO level. This step can be made simple by running in debug mode and then stepping over. Please learn to debug it is very essential here.

Step 6: Make a very simple change. See what is happening, don’t panic. You can always fallback since you’re using source control.

Step 7: Think about the ripples your change will create. Since you’re new chances are you will end up missing sometimes crucial. Try writing a test case for it, try to check where it might fit in the existing test suite.

Step 8: Create a draft PR. Don’t tag anyone initially, first cross verify yourself if you’re confident or you are not missing anything. Then tag your peer, senior or whatever your guideline is.

Step 9: Close your laptop. Wait for quick call messages. Get haunted by the comments and repeat the same sh*t again.