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<li><a class="reference internal" href="#">Temporary directories and files</a><ul>
<li><a class="reference internal" href="#the-tmpdir-test-function-argument">The ‘tmpdir’ test function argument</a></li>
<li><a class="reference internal" href="#the-default-base-temporary-directory">The default base temporary directory</a></li>
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<div class="section" id="temporary-directories-and-files">
<span id="tmpdir"></span><span id="tmpdir-handling"></span><h1>Temporary directories and files<a class="headerlink" href="#temporary-directories-and-files" title="Permalink to this headline">¶</a></h1>
<div class="section" id="the-tmpdir-test-function-argument">
<h2>The ‘tmpdir’ test function argument<a class="headerlink" href="#the-tmpdir-test-function-argument" title="Permalink to this headline">¶</a></h2>
<p>You can use the <tt class="docutils literal"><span class="pre">tmpdir</span></tt> function argument which will
provide a temporary directory unique to the test invocation,
created in the <a class="reference internal" href="#base-temporary-directory">base temporary directory</a>.</p>
<p><tt class="docutils literal"><span class="pre">tmpdir</span></tt> is a <a class="reference external" href="http://py.rtfd.org/path.html">py.path.local</a> object which offers <tt class="docutils literal"><span class="pre">os.path</span></tt> methods
and more. Here is an example test usage:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c"># content of test_tmpdir.py</span>
<span class="kn">import</span> <span class="nn">os</span>
<span class="k">def</span> <span class="nf">test_create_file</span><span class="p">(</span><span class="n">tmpdir</span><span class="p">):</span>
<span class="n">p</span> <span class="o">=</span> <span class="n">tmpdir</span><span class="o">.</span><span class="n">mkdir</span><span class="p">(</span><span class="s">"sub"</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="s">"hello.txt"</span><span class="p">)</span>
<span class="n">p</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="s">"content"</span><span class="p">)</span>
<span class="k">assert</span> <span class="n">p</span><span class="o">.</span><span class="n">read</span><span class="p">()</span> <span class="o">==</span> <span class="s">"content"</span>
<span class="k">assert</span> <span class="nb">len</span><span class="p">(</span><span class="n">tmpdir</span><span class="o">.</span><span class="n">listdir</span><span class="p">())</span> <span class="o">==</span> <span class="mi">1</span>
<span class="k">assert</span> <span class="mi">0</span>
</pre></div>
</div>
<p>Running this would result in a passed test except for the last
<tt class="docutils literal"><span class="pre">assert</span> <span class="pre">0</span></tt> line which we use to look at values:</p>
<div class="highlight-python"><pre>$ py.test test_tmpdir.py
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5
collected 1 items
test_tmpdir.py F
================================= FAILURES =================================
_____________________________ test_create_file _____________________________
tmpdir = local('/tmp/pytest-323/test_create_file0')
def test_create_file(tmpdir):
p = tmpdir.mkdir("sub").join("hello.txt")
p.write("content")
assert p.read() == "content"
assert len(tmpdir.listdir()) == 1
> assert 0
E assert 0
test_tmpdir.py:7: AssertionError
========================= 1 failed in 0.02 seconds =========================</pre>
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<div class="section" id="the-default-base-temporary-directory">
<span id="base-temporary-directory"></span><h2>The default base temporary directory<a class="headerlink" href="#the-default-base-temporary-directory" title="Permalink to this headline">¶</a></h2>
<p>Temporary directories are by default created as sub-directories of
the system temporary directory. The base name will be <tt class="docutils literal"><span class="pre">pytest-NUM</span></tt> where
<tt class="docutils literal"><span class="pre">NUM</span></tt> will be incremented with each test run. Moreover, entries older
than 3 temporary directories will be removed.</p>
<p>You can override the default temporary directory setting like this:</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">basetemp</span><span class="o">=</span><span class="n">mydir</span>
</pre></div>
</div>
<p>When distributing tests on the local machine, <tt class="docutils literal"><span class="pre">py.test</span></tt> takes care to
configure a basetemp directory for the sub processes such that all temporary
data lands below a single per-test run basetemp directory.</p>
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