Testing Express Apps with Jest and Supertest

How do you know that a change to one route did not break another route? You can start the server and click through every endpoint in Postman after each change, but that takes minutes, and it is easy to skip when time is short. An automated test sends the same requests in about a second and reports a failure, with the expected and the received value, when a response changes.

This chapter covers three ways to find problems in an Express application: tests that catch them before release, debuggers that show what the code is doing, and logs that record what happened in a running server