test skeleton for backend with some simple tests

[HansKallekleiv]

A first sketch on how to organize tests.

• Added a folder structure under tests with unit and integration. Subfolders are mirroring the code base. E.g. integration/services/sumo_access

• Added one example of unit test and one integration test towards Sumo using interactive token.

• Moved some code out of parameter_access into a utility function.

To run the tests:

sumo_login -e dev
pytest

• No tests added on the api itself. Should be discussed how/if we want to test the endpoints.
• If we want to test against Sumo we need to handle authentication in github actions and docker-compose. For github actions an option is to use service principal. https://learn.microsoft.com/en-us/azure/developer/github/connect-from-azure?tabs=azure-portal%2Cwindows#use-the-azure-login-action-with-a-service-principal-secret
  Example from fmu-sumo here: https://github.com/equinor/fmu-sumo/blob/main/.github/workflows/run_tests.yaml

[sigurdp]

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