python/mock-1.0.0/html/sentinel.html
author Carsten "Tomcat" Book <cbook@mozilla.com>
Tue, 30 Jun 2015 10:30:51 +0200
changeset 274663 79800010be78122db7c36d4b5833814fdbf28495
parent 112588 5981ff9d3f45de802d956b2f8e064f49b74cb7a6
permissions -rw-r--r--
Backed out changeset f41a2121425f (bug 1171931) for bustage


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  <div class="section" id="sentinel">
<h1>Sentinel<a class="headerlink" href="#sentinel" title="Permalink to this headline"></a></h1>
<dl class="data">
<dt id="mock.sentinel">
<tt class="descname">sentinel</tt><a class="headerlink" href="#mock.sentinel" title="Permalink to this definition"></a></dt>
<dd><p>The <tt class="docutils literal"><span class="pre">sentinel</span></tt> object provides a convenient way of providing unique
objects for your tests.</p>
<p>Attributes are created on demand when you access them by name. Accessing
the same attribute will always return the same object. The objects
returned have a sensible repr so that test failure messages are readable.</p>
</dd></dl>

<dl class="data">
<dt id="mock.DEFAULT">
<tt class="descname">DEFAULT</tt><a class="headerlink" href="#mock.DEFAULT" title="Permalink to this definition"></a></dt>
<dd><p>The <cite>DEFAULT</cite> object is a pre-created sentinel (actually
<cite>sentinel.DEFAULT</cite>). It can be used by <a class="reference internal" href="mock.html#mock.Mock.side_effect" title="mock.Mock.side_effect"><tt class="xref py py-attr docutils literal"><span class="pre">side_effect</span></tt></a>
functions to indicate that the normal return value should be used.</p>
</dd></dl>

<div class="section" id="sentinel-example">
<h2>Sentinel Example<a class="headerlink" href="#sentinel-example" title="Permalink to this headline"></a></h2>
<p>Sometimes when testing you need to test that a specific object is passed as an
argument to another method, or returned. It can be common to create named
sentinel objects to test this. <cite>sentinel</cite> provides a convenient way of
creating and testing the identity of objects like this.</p>
<p>In this example we monkey patch <cite>method</cite> to return
<cite>sentinel.some_object</cite>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">real</span> <span class="o">=</span> <span class="n">ProductionClass</span><span class="p">()</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">real</span><span class="o">.</span><span class="n">method</span> <span class="o">=</span> <span class="n">Mock</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s">&quot;method&quot;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">real</span><span class="o">.</span><span class="n">method</span><span class="o">.</span><span class="n">return_value</span> <span class="o">=</span> <span class="n">sentinel</span><span class="o">.</span><span class="n">some_object</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">result</span> <span class="o">=</span> <span class="n">real</span><span class="o">.</span><span class="n">method</span><span class="p">()</span>
<span class="gp">&gt;&gt;&gt; </span><span class="k">assert</span> <span class="n">result</span> <span class="ow">is</span> <span class="n">sentinel</span><span class="o">.</span><span class="n">some_object</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">sentinel</span><span class="o">.</span><span class="n">some_object</span>
<span class="go">sentinel.some_object</span>
</pre></div>
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<li><a class="reference internal" href="#">Sentinel</a><ul>
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