experimental py.test plugin for managing processes across test runs


install via:

pip install pytest-xprocess

This will provide a xprocess fixture which helps you to ensure that one ore more longer-running processes are present for your tests. You can use it to start and pre-configure test-specific databases (Postgres, Couchdb, ...).

Additionally there are two new command line options:

--xkill  # kills all external processes
--xshow  # shows currently running processes and log files

xprocess fixture usage

You typically define a project-specific fixture which uses the xprocess fixture internally:

# content of

import pytest

def myserver(xprocess):
    def preparefunc(cwd):
        return ("PATTERN", [subprocess args])

    logfile = xprocess.ensure("myserver", preparefunc)
    conn = # create a connection or url/port info to the server
    return conn

The xprocess.ensure function takes a name for the external process because you can have multiple external processes.

The preparefunc is a function which gets the current working directory and returns a (PATTERN, args, env) tuple. If the server has not yet been started:

  • the returned args are used to perform a subprocess invocation with environment env (a mapping) and redirect its stdout to a new logfile
  • the PATTERN is waited for in the logfile before returning. It should thus match a state of your server where it is ready to answer queries.
  • the logfile is returned pointing to the line right after the match

else, if the server is already running simply the logfile is returned.

To inherit the main test process environment, return None for env, or omit it and return just (PATTERN, args) from the preparefunc.

Note that the plugin needs to persist the process ID and logfile information. It does this in a sub directory of the directory which contains a pytest.ini or file.


The repository of this plugin is at

For more info on py.test see