Implement unit testing on my models

Hi,
I am trying to set up unit testing for my models, I have source data in PG, and my base model selects raw data by a certain date(configured in vars), then I have an intermediate and a final model on top of it.
I want to mock edge cases as raw data in certain columns and check if I get the same results as expected in a final model.
I didn’t find any good example of it.