Testing REST backend services

It's now time to turn our attention to the user authentication service. We've mentioned tests of this service, saying that we'll get to them later. We had developed some scripts for ad hoc testing, which have been useful all along. But later is now, and it's time to get cracking on some real tests.

There's a question of which tool to use for testing the authentication service. Mocha does a good job of organizing a series of test cases, and we should reuse it here. But the thing we have to test is a REST service. The customer of this service, the Notes application, uses it through the REST API, giving us a perfect rationalization to test at the REST interface. Our ad hoc scripts used the SuperAgent library to simplify making REST API calls. There happens to be a companion library, SuperTest, that is meant for REST API testing. Read its documentation here: https://www.npmjs.com/package/supertest.

We've already made the test-compose/userauth directory. In that directory...