How to test dockerized Flask-Cognito microservice?

I need test a dockerized Flask-Cognito application.

My requirements are:

  • Test running docker container as a black box.
  • It means test only Flask endpoints.
  • I would like avoid some changes in the code (during the testing). Best way is to emulate AWS Cognito service.
  • OPTIONAL: I would like to use Tavern or something similar.

I found emulators such as:

But I do not know how to use them.

Source: StackOverflow