1. Dmitrijs Milajevs
  2. pytest-xdist


xdist: pytest distributed testing plugin =============================================================== The `pytest-xdist`_ plugin extends py.test with some unique test execution modes: * test run parallelization_: if you have multiple CPUs or hosts you can use those for a combined test run. This allows to speed up development or to use special resources of `remote machines`_. * ``--boxed``: (not available on Windows) run each test in a boxed_ subprocess to survive ``SEGFAULTS`` or otherwise dying processes * ``--looponfail``: run your tests repeatedly in a subprocess. After each run py.test waits until a file in your project changes and then re-runs the previously failing tests. This is repeated until all tests pass after which again a full run is performed. * `Multi-Platform`_ coverage: you can specify different Python interpreters or different platforms and run tests in parallel on all of them. Before running tests remotely, ``py.test`` 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. Installation ----------------------- Install the plugin with:: easy_install pytest-xdist # or pip install pytest-xdist or use the package in develope/in-place mode with a checkout of the `pytest-xdist repository`_ :: python setup.py develop Usage examples --------------------- .. _parallelization: Speed up test runs by sending tests to multiple CPUs +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 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. Running tests in a Python subprocess +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ To instantiate a python2.5 sub process and send tests to it, you may type:: py.test -d --tx popen//python=python2.5 This will start a subprocess which is run with the "python2.5" Python interpreter, found in your system binary lookup path. If you prefix the --tx option value like this:: --tx 3*popen//python=python2.5 then three subprocesses would be created and tests will be load-balanced across these three processes. .. _boxed: Running tests in a boxed subprocess +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ If you have tests involving C or C++ libraries you might have to deal with tests crashing the process. For this case you max use the boxing options:: py.test --boxed which will run each test in a subprocess and will report if a test crashed the process. You can also combine this option with running multiple processes to speed up the test run and use your CPU cores:: py.test -n3 --boxed this would run 3 testing subprocesses in parallel which each create new boxed subprocesses for each test. .. _`remote machines`: Sending tests to remote SSH accounts +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 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. **NOTE:** For py.test to collect and send tests correctly you not only need to make sure all code and tests directories are rsynced, but that any test (sub) directory also has an ``__init__.py`` file because internally py.test references tests as a fully qualified python module path. **You will otherwise get strange errors** during setup of the remote side. Sending tests to remote Socket Servers +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 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= --rsyncdir mypkg mypkg .. _`atonce`: .. _`Multi-Platform`: Running tests on many platforms at once +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 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`_. .. _`xspec syntax`: http://codespeak.net/execnet/trunk/basics.html#xspec .. _`socketserver.py`: http://bitbucket.org/hpk42/execnet/raw/2af991418160/execnet/script/socketserver.py .. _`execnet`: http://codespeak.net/execnet Specifying test exec environments in an ini file +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ pytest (since version 2.0) supports ini-style cofiguration. You can for example make running with three subprocesses your default like this:: [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:: py.test --dist=each to run tests in each of the environments. Specifying "rsync" dirs in an ini-file +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 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. .. _`pytest-xdist`: http://pypi.python.org/pypi/pytest-xdist .. _`pytest-xdist repository`: http://bitbucket.org/hpk42/pytest-xdist .. _`pytest`: http://pytest.org Issue and Bug Tracker ------------------------ Please use the pytest issue tracker for bugs in this plugin, see https://bitbucket.org/hpk42/pytest/issues .