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<h3><a href="contents.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">xdist: pytest distributed testing plugin</a><ul>
<li><a class="reference internal" href="#installation-of-xdist-plugin">Installation of xdist plugin</a></li>
<li><a class="reference internal" href="#usage-examples">Usage examples</a><ul>
<li><a class="reference internal" href="#speed-up-test-runs-by-sending-tests-to-multiple-cpus">Speed up test runs by sending tests to multiple CPUs</a></li>
<li><a class="reference internal" href="#running-tests-in-a-python-subprocess">Running tests in a Python subprocess</a></li>
<li><a class="reference internal" href="#running-tests-in-looponfailing-mode">Running tests in looponfailing mode</a></li>
<li><a class="reference internal" href="#sending-tests-to-remote-ssh-accounts">Sending tests to remote SSH accounts</a></li>
<li><a class="reference internal" href="#sending-tests-to-remote-socket-servers">Sending tests to remote Socket Servers</a></li>
<li><a class="reference internal" href="#running-tests-on-many-platforms-at-once">Running tests on many platforms at once</a></li>
<li><a class="reference internal" href="#specifying-test-exec-environments-in-an-ini-file">Specifying test exec environments in an ini file</a></li>
<li><a class="reference internal" href="#specifying-rsync-dirs-in-an-ini-file">Specifying “rsync” dirs in an ini-file</a></li>
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<div class="section" id="xdist-pytest-distributed-testing-plugin">
<span id="xdist"></span><h1>xdist: pytest distributed testing plugin<a class="headerlink" href="#xdist-pytest-distributed-testing-plugin" title="Permalink to this headline">¶</a></h1>
<p>The <a class="reference external" href="http://pypi.python.org/pypi/pytest-xdist">pytest-xdist</a> plugin extends py.test with some unique
test execution modes:</p>
<ul class="simple">
<li>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. At this point a full run is again performed.</li>
<li>multiprocess Load-balancing: if you have multiple CPUs or hosts you can use
them for a combined test run. This allows to speed up
development or to use special resources of remote machines.</li>
<li>Multi-Platform coverage: you can specify different Python interpreters
or different platforms and run tests in parallel on all of them.</li>
</ul>
<p>Before running tests remotely, <tt class="docutils literal"><span class="pre">py.test</span></tt> 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.</p>
<div class="section" id="installation-of-xdist-plugin">
<h2>Installation of xdist plugin<a class="headerlink" href="#installation-of-xdist-plugin" title="Permalink to this headline">¶</a></h2>
<p>Install the plugin with:</p>
<div class="highlight-python"><pre>easy_install pytest-xdist
# or
pip install pytest-xdist</pre>
</div>
<p>or use the package in develop/in-place mode with
a checkout of the <a class="reference external" href="http://bitbucket.org/hpk42/pytest-xdist">pytest-xdist repository</a></p>
<div class="highlight-python"><pre>python setup.py develop</pre>
</div>
</div>
<div class="section" id="usage-examples">
<h2>Usage examples<a class="headerlink" href="#usage-examples" title="Permalink to this headline">¶</a></h2>
<div class="section" id="speed-up-test-runs-by-sending-tests-to-multiple-cpus">
<span id="xdistcpu"></span><h3>Speed up test runs by sending tests to multiple CPUs<a class="headerlink" href="#speed-up-test-runs-by-sending-tests-to-multiple-cpus" title="Permalink to this headline">¶</a></h3>
<p>To send tests to multiple CPUs, type:</p>
<div class="highlight-python"><pre>py.test -n NUM</pre>
</div>
<p>Especially for longer running tests or tests requiring
a lot of I/O this can lead to considerable speed ups.</p>
</div>
<div class="section" id="running-tests-in-a-python-subprocess">
<h3>Running tests in a Python subprocess<a class="headerlink" href="#running-tests-in-a-python-subprocess" title="Permalink to this headline">¶</a></h3>
<p>To instantiate a Python-2.4 subprocess and send tests to it, you may type:</p>
<div class="highlight-python"><pre>py.test -d --tx popen//python=python2.4</pre>
</div>
<p>This will start a subprocess which is run with the “python2.4”
Python interpreter, found in your system binary lookup path.</p>
<p>If you prefix the –tx option value like this:</p>
<div class="highlight-python"><pre>py.test -d --tx 3*popen//python=python2.4</pre>
</div>
<p>then three subprocesses would be created and the tests
will be distributed to three subprocesses and run simultanously.</p>
</div>
<div class="section" id="running-tests-in-looponfailing-mode">
<span id="looponfailing"></span><h3>Running tests in looponfailing mode<a class="headerlink" href="#running-tests-in-looponfailing-mode" title="Permalink to this headline">¶</a></h3>
<p>For refactoring a project with a medium or large test suite
you can use the looponfailing mode. Simply add the <tt class="docutils literal"><span class="pre">--f</span></tt> option:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">py</span><span class="o">.</span><span class="n">test</span> <span class="o">-</span><span class="n">f</span>
</pre></div>
</div>
<p>and py.test 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 <tt class="docutils literal"><span class="pre">looponfailingroots</span></tt> 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:</p>
<div class="highlight-python"><pre># content of a pytest.ini, setup.cfg or tox.ini file
[pytest]
looponfailroots = mypkg testdir</pre>
</div>
<p>This would lead to only looking for file changes in the respective directories, specified relatively to the ini-file’s directory.</p>
</div>
<div class="section" id="sending-tests-to-remote-ssh-accounts">
<h3>Sending tests to remote SSH accounts<a class="headerlink" href="#sending-tests-to-remote-ssh-accounts" title="Permalink to this headline">¶</a></h3>
<p>Suppose you have a package <tt class="docutils literal"><span class="pre">mypkg</span></tt> which contains some
tests that you can successfully run locally. And you also
have a ssh-reachable machine <tt class="docutils literal"><span class="pre">myhost</span></tt>. Then
you can ad-hoc distribute your tests by typing:</p>
<div class="highlight-python"><pre>py.test -d --tx ssh=myhostpopen --rsyncdir mypkg mypkg</pre>
</div>
<p>This will synchronize your <tt class="docutils literal"><span class="pre">mypkg</span></tt> package directory
with a remote ssh account and then collect and run your
tests at the remote side.</p>
<p>You can specify multiple <tt class="docutils literal"><span class="pre">--rsyncdir</span></tt> directories
to be sent to the remote side.</p>
</div>
<div class="section" id="sending-tests-to-remote-socket-servers">
<h3>Sending tests to remote Socket Servers<a class="headerlink" href="#sending-tests-to-remote-socket-servers" title="Permalink to this headline">¶</a></h3>
<p>Download the single-module <a class="reference external" href="http://bitbucket.org/hpk42/execnet/raw/2af991418160/execnet/script/socketserver.py">socketserver.py</a> Python program
and run it like this:</p>
<div class="highlight-python"><pre>python socketserver.py</pre>
</div>
<p>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:</p>
<div class="highlight-python"><pre>py.test -d --tx socket=192.168.1.102:8888 --rsyncdir mypkg mypkg</pre>
</div>
</div>
<div class="section" id="running-tests-on-many-platforms-at-once">
<span id="atonce"></span><h3>Running tests on many platforms at once<a class="headerlink" href="#running-tests-on-many-platforms-at-once" title="Permalink to this headline">¶</a></h3>
<p>The basic command to run tests on multiple platforms is:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">py</span><span class="o">.</span><span class="n">test</span> <span class="o">--</span><span class="n">dist</span><span class="o">=</span><span class="n">each</span> <span class="o">--</span><span class="n">tx</span><span class="o">=</span><span class="n">spec1</span> <span class="o">--</span><span class="n">tx</span><span class="o">=</span><span class="n">spec2</span>
</pre></div>
</div>
<p>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 <a class="reference external" href="http://codespeak.net/execnet/basics.html#xspec">xspec syntax</a>.</p>
</div>
<div class="section" id="specifying-test-exec-environments-in-an-ini-file">
<h3>Specifying test exec environments in an ini file<a class="headerlink" href="#specifying-test-exec-environments-in-an-ini-file" title="Permalink to this headline">¶</a></h3>
<p>pytest (since version 2.0) supports ini-style configuration.
For example, you could make running with three subprocesses your default:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="p">[</span><span class="n">pytest</span><span class="p">]</span>
<span class="n">addopts</span> <span class="o">=</span> <span class="o">-</span><span class="n">n3</span>
</pre></div>
</div>
<p>You can also add default environments like this:</p>
<div class="highlight-python"><pre>[pytest]
addopts = --tx ssh=myhost//python=python2.5 --tx ssh=myhost//python=python2.6</pre>
</div>
<p>and then just type:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">py</span><span class="o">.</span><span class="n">test</span> <span class="o">--</span><span class="n">dist</span><span class="o">=</span><span class="n">each</span>
</pre></div>
</div>
<p>to run tests in each of the environments.</p>
</div>
<div class="section" id="specifying-rsync-dirs-in-an-ini-file">
<h3>Specifying “rsync” dirs in an ini-file<a class="headerlink" href="#specifying-rsync-dirs-in-an-ini-file" title="Permalink to this headline">¶</a></h3>
<p>In a <tt class="docutils literal"><span class="pre">tox.ini</span></tt> or <tt class="docutils literal"><span class="pre">setup.cfg</span></tt> file in your root project directory
you may specify directories to include or to exclude in synchronisation:</p>
<div class="highlight-python"><pre>[pytest]
rsyncdirs = . mypkg helperpkg
rsyncignore = .hg</pre>
</div>
<p>These directory specifications are relative to the directory
where the configuration file was found.</p>
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