Tests run on Travis CI don't do any integration tests of a Lumen application

[HenkPoley]

Ref: https://github.com/albertcht/lumen-testing/issues/13#issuecomment-570165431

Meaning any function that is used to test a Lumen JSON API might be broken at any point.

Even though that is kind of the core use case of Lumen, in my opinion. Lumen slogan:

Lightning fast micro-services and APIs delivered with the elegance you expect.