conftest.py

import os
import tempfile
import pytest


@pytest.fixture()
def file_data():
    yield "2020-01-18T13:49:47,text"


@pytest.fixture()
def existing_file():
    with tempfile.NamedTemporaryFile("w") as tmp_file:
        file_name = tmp_file.name

    with open(file_name, 'w') as f:
        f.write("Test, data")

    yield file_name

    os.remove(file_name)