Unit, Integration and Functional Testing

I am working on Test Case and I would like to get clarity about which are the directories & files that come under,

1. Unit Testing.
2. Integration Testing.
3. Functional Testing.

My application architecture is as follows,

• controllers (which controls the respective action by calling service file from services directory).
• models (model for data tables).
• routes (for routing).
• services (a layer that communicates with model).
• db (holds migration for the database).
• index.js (which runs the server).

Could anyone help me out by saying which directories & files needs which type of testing (Unit, Integration, Functional)?

Thank you.