In PR #149 the task of writing pytests for D1 was started. This task is however not finished. After the next MVS release, following should be done:

• solve input and output flow issue of tranformer --> see Redefine transformer behavior (fix assignment to in- and output flows)  #389
• finish tests for transformer functions
• write tests for source functions --> will be done in Tests for source functions in D1 #391