I'm writing tests for an Express.js app and I don't know how to choose between unit tests and integration tests.
currently I experimented with:
unit tests - using Sinon for stubs/mocks/spies and Injects for dependency injection to modules. with this approach I have to stub MongoDB and other external methods.
I thought about unit testing the individual routes and then using an integration test to verify that the correct routes are actually invoked.
integration tests - using Supertest and Superagent, much less code to write (no need to mock/stub anything) but a test environment should exist (databases, etc..)
I'm using Mocha to run both styles of tests.
how should I choose between those two different approaches ?
You should probably do both. Unit test each non-helper method that does non-trivial work. Run the whole thing through a few integration tests. If you find yourself having to do tons and tons and tons of mocks and stubs, it's probably a sign to refactor.