[Python] Issue with pytest: ImportError - attempted relative import with no known parent...

I'm working with pytest in a FastAPI project and trying to run unit tests.

Project Structure:

app
└── fastapi_app
├── __init__.py
├── celery_worker.py
├── Dockerfile
├── main.py
├── middlewares
│ ├── middlewares.py
├── requirements.txt
├── routes
│ ├── process.py
├── tests
│ ├── test_process.py


I run pytest from the app directory:

(venv) PS C:\Users\Administrador\Desktop\code\repo\fastapi_celery_redis\app> pytest


But I get the following error:

================================================= test session starts =================================================
platform win32 -- Python 3.13.2, pytest-8.3.4, pluggy-1.5.0
rootdir: C:\Users\Administrador\Desktop\code\repo\fastapi_celery_redis\app
plugins: anyio-4.8.0
collected 0 items / 1 error

======================================================= ERRORS ========================================================
_________________________________ ERROR collecting fastapi_app/tests/test_process.py __________________________________
ImportError while importing test module 'C:\Users\Administrador\Desktop\code\repo\fastapi_celery_redis\app\fastapi_app\tests\test_process.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
..\..\..\..\..\AppData\Local\Programs\Python\Python313\Lib\importlib\__init__.py:88: in import_module
return _bootstrap._gcd_import(name[level:], package, level)
fastapi_app\tests\test_process.py:3: in <module>
from ..main import app
E ImportError: attempted relative import with no known parent package
=============================================== short test summary info ===============================================
ERROR fastapi_app/tests/test_process.py
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
================================================== 1 error in 0.90s ===================================================


test_process.py content:

import pytest
from fastapi.testclient import TestClient
from ..main import app

# Cliente de pruebas
client = TestClient(app)

def test_add_task_success():
"""Prueba cuando la tarea se envía exitosamente"""
data = {"number": 10, "text": "Test task"}
response = client.post("/add-task", json=data)

assert response.status_code == 200
result = response.json()
assert result["error"] is False
assert result["message"] == "Tarea enviada exitosamente"
assert result["result"]["message"] == "Tarea enviada"



What I've Tried So Far:

1. Running pytest from both app and fastapi_app directories.
2. Changing the import in test_process.py to an absolute import

from fastapi_app.main import app



None of these have solved the issue. How can I properly import app in my test file and make pytest recognize my package structure?

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