Best or proper way to pass python object into pytest

[AndrewFalanga]

Hi,

I'm invoking pytest via the pytest.main(...) call. From the invoking python, I need to pass an object reference into the tests so that they may make use of the functions. In condensed form, this is what I'm doing now:

# File: object_reference.py

class ObjRef:
    def __init__(self, obj):
        find_name = lambda o, n: getattr(obj, n, self.throw_up) if obj else self.throw_up
        self.find_data = find_name(obj, 'find_data')
        ...
    def throw_up(self):
        raise NotImplementedError

# then: in main test code
import pytest
import object_reference

class TestExecutor:
    # has lots of methods and properties
    def __init__(self):
        self.comm = SomeCommThing()
    
    def execute(self):
        ref = object_reference.ObjRef(self.comm)
        pytest.main([...], plugins = [ref])

As you can see, the ObjRef object isn't truly a plugin. This truly is the simplest way of passing an object with a list of callbacks that the tests make use of (as opposed to somehow making the tests import and instantiate). However, is there a better method? I've spent much time Googling and this is the best I've found thus far. "Callable modules" aren't really a thing without a lot of black magic programming.

[RonnyPfannschmidt]

The simplest way to pass a object in is a plugin which provides a fixture

Plugins can be a instance of a class

Methods can be marked as fixtures

[nicoddemus]

To exemplify what @RonnyPfannschmidt said, something like this:

# then: in main test code
import pytest
import object_reference

@attr.define 
class MyPlugin:
   _ref: object_reference.ObjRef

   @pytest.fixture
   def ref(self) -> object_reference.ObjRef:
       return self._ref

class TestExecutor:
    # has lots of methods and properties
    def __init__(self):
        self.comm = SomeCommThing()
    
    def execute(self):
        ref = object_reference.ObjRef(self.comm)
        pytest.main([...], plugins = [MyPlugin(ref)])

Now your tests have access to a ref fixture.

[tilak-trinity]

Thanks for this detailed answer:

I have a similar use case- Wherein I need to pass a function during pytest call. below is my implementation. I get an error wrapper not defined
Any help is appreciated. Below is the reference code

File main.py

import method_x

#define variables  a , b

class MyPlugin:               
        @pytest.fixture
         def wrapper():
               obj=method_x(var_1= a, var_2= b)
               return obj 

        
print("testing starts")
ref= MyPlugin(wrapper)

Invoking pytest

pytest.main(plugins=[ref])