How to test express config?

I've been trying to figure out how to test the configuration for an express server (ex. middleware, etc.). I haven't been able to find any examples, and I'm unsure if the best way to test it is to simply match the expected list of middleware to the actual list of middleware, do something else entirely, or even if it's just config that shouldn't be tested at all.

I should also add that I'm not as interested in how exactly to do it, but rather more in the higher level concept. But I'm using mocha and supertest if it helps.