Problem with using pytest

[anisak000]

In the Particle-Simulator Repo, the Quarks file, there is a test_quark.py file that tests the code in the quark.py file. However, when I run pytest, I get the following error message:

def test_quark_1():

  assert t.flip("up") == "down"

E TypeError: flip() takes 1 positional argument but 2 were given

The online explanation that "t" which is the class acts as a separate argument is a problem because how else would the assertion be made (I tried other ways too). I would most appreciate it if someone could give some advice on how to resolve the problem.