How to access a method from pytest, if there's no explicit root package or module

Simply speaking, I have this directory structure:

src/
  my_file1.py

tests/
  __init__.py
  my_file1_test.py

In my_file1.py:

def my_func1(a):
  return a + 99

How do I then access my_func1 from the tests? In my_file1_test.py I can't access the method:

# from ??? import ?? # is this needed at all?

def my_test1():
  res = my_func1(123) # unaccessible
  assert res = 222

Will I have to create __init__.py in scr directory first?

from src.myfile import my_func1

===>

ModuleNotFoundError: No module named 'scr' 

And if I add __init__.py then it'll become:

ImportError: cannot import name 'my_func1' from 'src'