py.test can ad-hoc distribute test runs to multiple CPUs or remote machines. This allows to speed up development or to use special resources of remote machines. Before running tests remotely, py.test efficiently synchronizes your program source code to the remote place. All test results are reported back and displayed to your local test session. You may specify different Python versions and interpreters.
Requirements: you need to install the execnet package (at least version 1.0.0b4) to perform distributed test runs.
NOTE: Version 1.1.x is not able to distribute tests across Python3/Python2 barriers.
To send tests to multiple CPUs, type:
py.test -n NUM
Especially for longer running tests or tests requiring a lot of IO this can lead to considerable speed ups.
To instantiate a python2.4 sub process and send tests to it, you may type:
py.test -d --tx popen//python=python2.4
This will start a subprocess which is run with the "python2.4" Python interpreter, found in your system binary lookup path.
If you prefix the --tx option value like this:
--tx 3*popen//python=python2.4
then three subprocesses would be created and tests will be load-balanced across these three processes.
Suppose you have a package mypkg which contains some tests that you can successfully run locally. And you have a ssh-reachable machine myhost. Then you can ad-hoc distribute your tests by typing:
py.test -d --tx ssh=myhostpopen --rsyncdir mypkg mypkg
This will synchronize your mypkg package directory to an remote ssh account and then locally collect tests and send them to remote places for execution.
You can specify multiple --rsyncdir directories to be sent to the remote side.
Download the single-module socketserver.py Python program and run it like this:
python socketserver.py
It will tell you that it starts listening on the default port. You can now on your home machine specify this new socket host with something like this:
py.test -d --tx socket=192.168.1.102:8888 --rsyncdir mypkg mypkg
The basic command to run tests on multiple platforms is:
py.test --dist=each --tx=spec1 --tx=spec2
If you specify a windows host, an OSX host and a Linux environment this command will send each tests to all platforms - and report back failures from all platforms at once. The specifications strings use the xspec syntax.
Instead of specifying command line options, you can put options values in a conftest.py file like this:
pytest_option_tx = ['ssh=myhost//python=python2.5', 'popen//python=python2.5'] pytest_option_dist = True
Any commandline --tx specifictions will add to the list of available execution environments.
In your mypkg/conftest.py you may specify directories to synchronise or to exclude:
rsyncdirs = ['.', '../plugins'] rsyncignore = ['_cache']
These directory specifications are relative to the directory where the conftest.py is found.