Create individual test for the functions that creates the constraints in the model

[datejada]

What and Why

We want to add tests for each function that creates constraints that do not depend on the case studies (as it currently does). For instance, to test the ramping constraints, we have the Norse case with some input data that creates the constraint. But we would like to have a test that, given some inputs, returns the expected constraint (maybe without running the full energy problem).

This approach is similar to the one in SpineOpt (which is a good practice there)

Possible Drawbacks

• It increases the number of tests
• It might be not easy to set up the first time.

Related Issues

Blocked by #701