pytest: how to make dedicated test directory
Question: I want next project structure:

    
    
    |--folder/
    |  |--tests/
    |  |--project/
    

Lets write simple example:

    
    
    |--test_pytest/
    |  |--tests/
    |  |  |--test_sum.py
    |  |--t_pytest/
    |  |  |--sum.py
    |  |  |--__init__.py
    

sum.py:

    
    
    def my_sum(a, b):
        return a + b
    

test_sum.py:

    
    
    from t_pytest.sum import my_sum
    def test_my_sum():
        assert my_sum(2, 2) == 5, "math still works"
    

Let's run it:

    
    
    test_pytest$ py.test ./
    ========== test session starts ===========
    platform linux -- Python 3.4.3, pytest-2.9.2, py-1.4.31, pluggy-0.3.1
    rootdir: /home/step/test_pytest, inifile: 
    collected 0 items / 1 errors 
    
    ================= ERRORS =================
    ___ ERROR collecting tests/test_sum.py ___
    tests/test_sum.py:1: in <module>
        from t_pytest import my_sum
    E   ImportError: No module named 't_pytest'
    ======== 1 error in 0.01 seconds =========
    

It can't see t_pytest module. It was made like httpie  
<https://github.com/jkbrzt/httpie/>
<https://github.com/jkbrzt/httpie/blob/master/tests/test_errors.py>  
Why? How can I correct it?


Answer: Thank you, jonrsharpe. Py.test does no magic, I need to make my packages
importable myself. There is one of possible solutions:

    
    
       $ export PYTHONPATH="${PYTHONPATH}: [Path to folder with my module]"   
    

( PYTHONPATH is one of path sources for sys.path )  
If I need to make this change permanently, I need to add this string to
`~/.bashrc`

