The pytest-xdist plugin extends pytest with some unique test execution modes:
Before running tests remotely, pytest efficiently “rsyncs” your program source code to the remote place. All test results are reported back and displayed to your local terminal. You may specify different Python versions and interpreters.
Install the plugin with:
easy_install pytest-xdist # or pip install pytest-xdist
or use the package in develop/in-place mode with a checkout of the pytest-xdist repository
python setup.py develop
To send tests to multiple CPUs, type:
py.test -n NUM
Especially for longer running tests or tests requiring a lot of I/O this can lead to considerable speed ups.
To instantiate a Python-2.4 subprocess 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:
py.test -d --tx 3*popen//python=python2.4
then three subprocesses would be created and the tests will be distributed to three subprocesses and run simultanously.
For refactoring a project with a medium or large test suite you can use the looponfailing mode. Simply add the --f option:
and pytest will run your tests. Assuming you have failures it will then wait for file changes and re-run the failing test set. File changes are detected by looking at looponfailingroots root directories and all of their contents (recursively). If the default for this value does not work for you you can change it in your project by setting a configuration option:
# content of a pytest.ini, setup.cfg or tox.ini file [pytest] looponfailroots = mypkg testdir
This would lead to only looking for file changes in the respective directories, specified relatively to the ini-file’s directory.
Suppose you have a package mypkg which contains some tests that you can successfully run locally. And you also 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 with a remote ssh account and then collect and run your tests at the remote side.
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:
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.
pytest (since version 2.0) supports ini-style configuration. For example, you could make running with three subprocesses your default:
[pytest] addopts = -n3
You can also add default environments like this:
[pytest] addopts = --tx ssh=myhost//python=python2.5 --tx ssh=myhost//python=python2.6
and then just type:
to run tests in each of the environments.
In a tox.ini or setup.cfg file in your root project directory you may specify directories to include or to exclude in synchronisation:
[pytest] rsyncdirs = . mypkg helperpkg rsyncignore = .hg
These directory specifications are relative to the directory where the configuration file was found.