import logging

logger = logging.getLogger("my.plugin")

def pytest_runtestloop(session):
    logger.info("this is showing")

def pytest_sessionfinish(session, exitstatus):
    logger.info("this is not showing")

[pytest]
; logging options
log_cli = true
log_level = INFO
log_format = %(asctime)s %(name)s: %(levelname)s %(message)s