Allow environment variables in Unit tests

[LockenkopfConstr]

I would find it helpful to have environment variables in the unit test code field when I write more complex tests.

I want to refer to an user_id I declared as a enviroment variable. And I want to use outputs from previous API in further API calls in my test. For this case the refernce would be helpful, even though I can also just copy past the variable... It would be a quality of life feature.