Python, Py.Test, How can I prevent self from eating one of my test parameters? : I have in my test module:

    import pytest
    from src.model_code.central import AgentBasic

    class AgentBasicTestee(AgentBasic):
        pass

    @pytest.fixture()
    def agentBasic():
        return AgentBasicTestee()

    @pytest.mark.parametrize('alpha, beta, delta, expected', [
        (2, 1, 1, pytest.approx(0.5)),
        (2, 2, 2, pytest.approx(-0.9375 / 0.75)),
    ])  
    def test_b3(agentBasic, AgentCOne,alpha, beta, delta, expected):
        assert(agentBasic.b3(alpha, beta, delta) == expected)

and in my import module

    from src.model_code.crra_utility import AgentCrra
    AgentCOne = AgentCrra

    class AgentBasic:
    @staticmethod
    def b3(alpha, beta, delta):
        """define matric element b3"""
        k = AgentCOne.k_bar(alpha, beta, delta)
        c = AgentCOne.c_bar(alpha, beta, delta)
        return -c/k


The error message I get is: 
`>       c = AgentCOne.c_bar(alpha, beta, delta)
E       TypeError: c_bar() missing 1 required positional argument: 'delta'`
Note:

    def c_bar(self, alpha, beta, delta):
        """non-stochastic steady-state for consumption"""
        k = self.k_bar(alpha, beta, delta)
        return k ** alpha  - delta * k 

So far, self takes one of my parameters s.t. delta stays empty... How can i prevent hat?