Sandbox::https://fullstackopen.com/en/part4

In this part, we will continue our work on the backend. Our first major theme will be writing unit and integration tests for the backend. After we have covered testing, we will take a look at implementing user authentication and authorization.

Part updated 13th August 2025

Node updated to version v22.3.0
Express updated to version 5 and the express-async-errors library removed from part 4b
Small fixes and improvements

a Structure of backend application, introduction to testing

b Testing the backend

c User administration

d Token authentication

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