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<div class="section" id="module-doctest">
<span id="doctest-test-interactive-python-examples"></span><h1>27.3. <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> — Test interactive Python examples<a class="headerlink" href="#module-doctest" title="本標題的永久連結">¶</a></h1>
<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.7/Lib/doctest.py">Lib/doctest.py</a></p>
<hr class="docutils" />
<p>The <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> module searches for pieces of text that look like interactive
Python sessions, and then executes those sessions to verify that they work
exactly as shown. There are several common ways to use doctest:</p>
<ul class="simple">
<li>To check that a module’s docstrings are up-to-date by verifying that all
interactive examples still work as documented.</li>
<li>To perform regression testing by verifying that interactive examples from a
test file or a test object work as expected.</li>
<li>To write tutorial documentation for a package, liberally illustrated with
input-output examples. Depending on whether the examples or the expository text
are emphasized, this has the flavor of 「literate testing」 or 「executable
documentation」.</li>
</ul>
<p>Here’s a complete but small example module:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="sd">"""</span>
<span class="sd">This is the "example" module.</span>
<span class="sd">The example module supplies one function, factorial(). For example,</span>
<span class="sd">>>> factorial(5)</span>
<span class="sd">120</span>
<span class="sd">"""</span>
<span class="k">def</span> <span class="nf">factorial</span><span class="p">(</span><span class="n">n</span><span class="p">):</span>
<span class="sd">"""Return the factorial of n, an exact integer >= 0.</span>
<span class="sd"> >>> [factorial(n) for n in range(6)]</span>
<span class="sd"> [1, 1, 2, 6, 24, 120]</span>
<span class="sd"> >>> factorial(30)</span>
<span class="sd"> 265252859812191058636308480000000</span>
<span class="sd"> >>> factorial(-1)</span>
<span class="sd"> Traceback (most recent call last):</span>
<span class="sd"> ...</span>
<span class="sd"> ValueError: n must be >= 0</span>
<span class="sd"> Factorials of floats are OK, but the float must be an exact integer:</span>
<span class="sd"> >>> factorial(30.1)</span>
<span class="sd"> Traceback (most recent call last):</span>
<span class="sd"> ...</span>
<span class="sd"> ValueError: n must be exact integer</span>
<span class="sd"> >>> factorial(30.0)</span>
<span class="sd"> 265252859812191058636308480000000</span>
<span class="sd"> It must also not be ridiculously large:</span>
<span class="sd"> >>> factorial(1e100)</span>
<span class="sd"> Traceback (most recent call last):</span>
<span class="sd"> ...</span>
<span class="sd"> OverflowError: n too large</span>
<span class="sd"> """</span>
<span class="kn">import</span> <span class="nn">math</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">n</span> <span class="o">>=</span> <span class="mi">0</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s2">"n must be >= 0"</span><span class="p">)</span>
<span class="k">if</span> <span class="n">math</span><span class="o">.</span><span class="n">floor</span><span class="p">(</span><span class="n">n</span><span class="p">)</span> <span class="o">!=</span> <span class="n">n</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s2">"n must be exact integer"</span><span class="p">)</span>
<span class="k">if</span> <span class="n">n</span><span class="o">+</span><span class="mi">1</span> <span class="o">==</span> <span class="n">n</span><span class="p">:</span> <span class="c1"># catch a value like 1e300</span>
<span class="k">raise</span> <span class="ne">OverflowError</span><span class="p">(</span><span class="s2">"n too large"</span><span class="p">)</span>
<span class="n">result</span> <span class="o">=</span> <span class="mi">1</span>
<span class="n">factor</span> <span class="o">=</span> <span class="mi">2</span>
<span class="k">while</span> <span class="n">factor</span> <span class="o"><=</span> <span class="n">n</span><span class="p">:</span>
<span class="n">result</span> <span class="o">*=</span> <span class="n">factor</span>
<span class="n">factor</span> <span class="o">+=</span> <span class="mi">1</span>
<span class="k">return</span> <span class="n">result</span>
<span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s2">"__main__"</span><span class="p">:</span>
<span class="kn">import</span> <span class="nn">doctest</span>
<span class="n">doctest</span><span class="o">.</span><span class="n">testmod</span><span class="p">()</span>
</pre></div>
</div>
<p>If you run <code class="file docutils literal notranslate"><span class="pre">example.py</span></code> directly from the command line, <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a>
works its magic:</p>
<div class="highlight-shell-session notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> python example.py
<span class="gp">$</span>
</pre></div>
</div>
<p>There’s no output! That’s normal, and it means all the examples worked. Pass
<code class="docutils literal notranslate"><span class="pre">-v</span></code> to the script, and <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> prints a detailed log of what
it’s trying, and prints a summary at the end:</p>
<div class="highlight-shell-session notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> python example.py -v
<span class="go">Trying:</span>
<span class="go"> factorial(5)</span>
<span class="go">Expecting:</span>
<span class="go"> 120</span>
<span class="go">ok</span>
<span class="go">Trying:</span>
<span class="go"> [factorial(n) for n in range(6)]</span>
<span class="go">Expecting:</span>
<span class="go"> [1, 1, 2, 6, 24, 120]</span>
<span class="go">ok</span>
</pre></div>
</div>
<p>And so on, eventually ending with:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>Trying:
factorial(1e100)
Expecting:
Traceback (most recent call last):
...
OverflowError: n too large
ok
2 items passed all tests:
1 tests in __main__
8 tests in __main__.factorial
9 tests in 2 items.
9 passed and 0 failed.
Test passed.
$
</pre></div>
</div>
<p>That’s all you need to know to start making productive use of <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a>!
Jump in. The following sections provide full details. Note that there are many
examples of doctests in the standard Python test suite and libraries.
Especially useful examples can be found in the standard test file
<code class="file docutils literal notranslate"><span class="pre">Lib/test/test_doctest.py</span></code>.</p>
<div class="section" id="simple-usage-checking-examples-in-docstrings">
<span id="doctest-simple-testmod"></span><h2>27.3.1. Simple Usage: Checking Examples in Docstrings<a class="headerlink" href="#simple-usage-checking-examples-in-docstrings" title="本標題的永久連結">¶</a></h2>
<p>The simplest way to start using doctest (but not necessarily the way you’ll
continue to do it) is to end each module <code class="xref py py-mod docutils literal notranslate"><span class="pre">M</span></code> with:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s2">"__main__"</span><span class="p">:</span>
<span class="kn">import</span> <span class="nn">doctest</span>
<span class="n">doctest</span><span class="o">.</span><span class="n">testmod</span><span class="p">()</span>
</pre></div>
</div>
<p><a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> then examines docstrings in module <code class="xref py py-mod docutils literal notranslate"><span class="pre">M</span></code>.</p>
<p>Running the module as a script causes the examples in the docstrings to get
executed and verified:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">python</span> <span class="n">M</span><span class="o">.</span><span class="n">py</span>
</pre></div>
</div>
<p>This won’t display anything unless an example fails, in which case the failing
example(s) and the cause(s) of the failure(s) are printed to stdout, and the
final line of output is <code class="docutils literal notranslate"><span class="pre">***Test</span> <span class="pre">Failed***</span> <span class="pre">N</span> <span class="pre">failures.</span></code>, where <em>N</em> is the
number of examples that failed.</p>
<p>Run it with the <code class="docutils literal notranslate"><span class="pre">-v</span></code> switch instead:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">python</span> <span class="n">M</span><span class="o">.</span><span class="n">py</span> <span class="o">-</span><span class="n">v</span>
</pre></div>
</div>
<p>and a detailed report of all examples tried is printed to standard output, along
with assorted summaries at the end.</p>
<p>You can force verbose mode by passing <code class="docutils literal notranslate"><span class="pre">verbose=True</span></code> to <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a>, or
prohibit it by passing <code class="docutils literal notranslate"><span class="pre">verbose=False</span></code>. In either of those cases,
<code class="docutils literal notranslate"><span class="pre">sys.argv</span></code> is not examined by <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a> (so passing <code class="docutils literal notranslate"><span class="pre">-v</span></code> or not
has no effect).</p>
<p>There is also a command line shortcut for running <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a>. You can
instruct the Python interpreter to run the doctest module directly from the
standard library and pass the module name(s) on the command line:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">python</span> <span class="o">-</span><span class="n">m</span> <span class="n">doctest</span> <span class="o">-</span><span class="n">v</span> <span class="n">example</span><span class="o">.</span><span class="n">py</span>
</pre></div>
</div>
<p>This will import <code class="file docutils literal notranslate"><span class="pre">example.py</span></code> as a standalone module and run
<a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a> on it. Note that this may not work correctly if the file is
part of a package and imports other submodules from that package.</p>
<p>For more information on <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a>, see section <a class="reference internal" href="#doctest-basic-api"><span class="std std-ref">Basic API</span></a>.</p>
</div>
<div class="section" id="simple-usage-checking-examples-in-a-text-file">
<span id="doctest-simple-testfile"></span><h2>27.3.2. Simple Usage: Checking Examples in a Text File<a class="headerlink" href="#simple-usage-checking-examples-in-a-text-file" title="本標題的永久連結">¶</a></h2>
<p>Another simple application of doctest is testing interactive examples in a text
file. This can be done with the <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a> function:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">doctest</span>
<span class="n">doctest</span><span class="o">.</span><span class="n">testfile</span><span class="p">(</span><span class="s2">"example.txt"</span><span class="p">)</span>
</pre></div>
</div>
<p>That short script executes and verifies any interactive Python examples
contained in the file <code class="file docutils literal notranslate"><span class="pre">example.txt</span></code>. The file content is treated as if it
were a single giant docstring; the file doesn’t need to contain a Python
program! For example, perhaps <code class="file docutils literal notranslate"><span class="pre">example.txt</span></code> contains this:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>The ``example`` module
======================
Using ``factorial``
-------------------
This is an example text file in reStructuredText format. First import
``factorial`` from the ``example`` module:
>>> from example import factorial
Now use it:
>>> factorial(6)
120
</pre></div>
</div>
<p>Running <code class="docutils literal notranslate"><span class="pre">doctest.testfile("example.txt")</span></code> then finds the error in this
documentation:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">File</span> <span class="s2">"./example.txt"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">14</span><span class="p">,</span> <span class="ow">in</span> <span class="n">example</span><span class="o">.</span><span class="n">txt</span>
<span class="n">Failed</span> <span class="n">example</span><span class="p">:</span>
<span class="n">factorial</span><span class="p">(</span><span class="mi">6</span><span class="p">)</span>
<span class="n">Expected</span><span class="p">:</span>
<span class="mi">120</span>
<span class="n">Got</span><span class="p">:</span>
<span class="mi">720</span>
</pre></div>
</div>
<p>As with <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a>, <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a> won’t display anything unless an
example fails. If an example does fail, then the failing example(s) and the
cause(s) of the failure(s) are printed to stdout, using the same format as
<a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a>.</p>
<p>By default, <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a> looks for files in the calling module’s directory.
See section <a class="reference internal" href="#doctest-basic-api"><span class="std std-ref">Basic API</span></a> for a description of the optional arguments
that can be used to tell it to look for files in other locations.</p>
<p>Like <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a>, <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a>』s verbosity can be set with the
<code class="docutils literal notranslate"><span class="pre">-v</span></code> command-line switch or with the optional keyword argument
<em>verbose</em>.</p>
<p>There is also a command line shortcut for running <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a>. You can
instruct the Python interpreter to run the doctest module directly from the
standard library and pass the file name(s) on the command line:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">python</span> <span class="o">-</span><span class="n">m</span> <span class="n">doctest</span> <span class="o">-</span><span class="n">v</span> <span class="n">example</span><span class="o">.</span><span class="n">txt</span>
</pre></div>
</div>
<p>Because the file name does not end with <code class="file docutils literal notranslate"><span class="pre">.py</span></code>, <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> infers that
it must be run with <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a>, not <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a>.</p>
<p>For more information on <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a>, see section <a class="reference internal" href="#doctest-basic-api"><span class="std std-ref">Basic API</span></a>.</p>
</div>
<div class="section" id="how-it-works">
<span id="doctest-how-it-works"></span><h2>27.3.3. How It Works<a class="headerlink" href="#how-it-works" title="本標題的永久連結">¶</a></h2>
<p>This section examines in detail how doctest works: which docstrings it looks at,
how it finds interactive examples, what execution context it uses, how it
handles exceptions, and how option flags can be used to control its behavior.
This is the information that you need to know to write doctest examples; for
information about actually running doctest on these examples, see the following
sections.</p>
<div class="section" id="which-docstrings-are-examined">
<span id="doctest-which-docstrings"></span><h3>27.3.3.1. Which Docstrings Are Examined?<a class="headerlink" href="#which-docstrings-are-examined" title="本標題的永久連結">¶</a></h3>
<p>The module docstring, and all function, class and method docstrings are
searched. Objects imported into the module are not searched.</p>
<p>In addition, if <code class="docutils literal notranslate"><span class="pre">M.__test__</span></code> exists and 「is true」, it must be a dict, and each
entry maps a (string) name to a function object, class object, or string.
Function and class object docstrings found from <code class="docutils literal notranslate"><span class="pre">M.__test__</span></code> are searched, and
strings are treated as if they were docstrings. In output, a key <code class="docutils literal notranslate"><span class="pre">K</span></code> in
<code class="docutils literal notranslate"><span class="pre">M.__test__</span></code> appears with name</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="o"><</span><span class="n">name</span> <span class="n">of</span> <span class="n">M</span><span class="o">>.</span><span class="n">__test__</span><span class="o">.</span><span class="n">K</span>
</pre></div>
</div>
<p>Any classes found are recursively searched similarly, to test docstrings in
their contained methods and nested classes.</p>
<div class="impl-detail compound">
<p><strong>CPython implementation detail:</strong> Prior to version 3.4, extension modules written in C were not fully
searched by doctest.</p>
</div>
</div>
<div class="section" id="how-are-docstring-examples-recognized">
<span id="doctest-finding-examples"></span><h3>27.3.3.2. How are Docstring Examples Recognized?<a class="headerlink" href="#how-are-docstring-examples-recognized" title="本標題的永久連結">¶</a></h3>
<p>In most cases a copy-and-paste of an interactive console session works fine,
but doctest isn’t trying to do an exact emulation of any specific Python shell.</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="c1"># comments are ignored</span>
<span class="gp">>>> </span><span class="n">x</span> <span class="o">=</span> <span class="mi">12</span>
<span class="gp">>>> </span><span class="n">x</span>
<span class="go">12</span>
<span class="gp">>>> </span><span class="k">if</span> <span class="n">x</span> <span class="o">==</span> <span class="mi">13</span><span class="p">:</span>
<span class="gp">... </span> <span class="nb">print</span><span class="p">(</span><span class="s2">"yes"</span><span class="p">)</span>
<span class="gp">... </span><span class="k">else</span><span class="p">:</span>
<span class="gp">... </span> <span class="nb">print</span><span class="p">(</span><span class="s2">"no"</span><span class="p">)</span>
<span class="gp">... </span> <span class="nb">print</span><span class="p">(</span><span class="s2">"NO"</span><span class="p">)</span>
<span class="gp">... </span> <span class="nb">print</span><span class="p">(</span><span class="s2">"NO!!!"</span><span class="p">)</span>
<span class="gp">...</span>
<span class="go">no</span>
<span class="go">NO</span>
<span class="go">NO!!!</span>
<span class="go">>>></span>
</pre></div>
</div>
<p>Any expected output must immediately follow the final <code class="docutils literal notranslate"><span class="pre">'>>></span> <span class="pre">'</span></code> or <code class="docutils literal notranslate"><span class="pre">'...</span> <span class="pre">'</span></code>
line containing the code, and the expected output (if any) extends to the next
<code class="docutils literal notranslate"><span class="pre">'>>></span> <span class="pre">'</span></code> or all-whitespace line.</p>
<p>The fine print:</p>
<ul>
<li><p class="first">Expected output cannot contain an all-whitespace line, since such a line is
taken to signal the end of expected output. If expected output does contain a
blank line, put <code class="docutils literal notranslate"><span class="pre"><BLANKLINE></span></code> in your doctest example each place a blank line
is expected.</p>
</li>
<li><p class="first">All hard tab characters are expanded to spaces, using 8-column tab stops.
Tabs in output generated by the tested code are not modified. Because any
hard tabs in the sample output <em>are</em> expanded, this means that if the code
output includes hard tabs, the only way the doctest can pass is if the
<a class="reference internal" href="#doctest.NORMALIZE_WHITESPACE" title="doctest.NORMALIZE_WHITESPACE"><code class="xref py py-const docutils literal notranslate"><span class="pre">NORMALIZE_WHITESPACE</span></code></a> option or <a class="reference internal" href="#doctest-directives"><span class="std std-ref">directive</span></a>
is in effect.
Alternatively, the test can be rewritten to capture the output and compare it
to an expected value as part of the test. This handling of tabs in the
source was arrived at through trial and error, and has proven to be the least
error prone way of handling them. It is possible to use a different
algorithm for handling tabs by writing a custom <a class="reference internal" href="#doctest.DocTestParser" title="doctest.DocTestParser"><code class="xref py py-class docutils literal notranslate"><span class="pre">DocTestParser</span></code></a> class.</p>
</li>
<li><p class="first">Output to stdout is captured, but not output to stderr (exception tracebacks
are captured via a different means).</p>
</li>
<li><p class="first">If you continue a line via backslashing in an interactive session, or for any
other reason use a backslash, you should use a raw docstring, which will
preserve your backslashes exactly as you type them:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="n">x</span><span class="p">):</span>
<span class="gp">... </span> <span class="sa">r</span><span class="sd">'''Backslashes in a raw docstring: m\n'''</span>
<span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="vm">__doc__</span><span class="p">)</span>
<span class="go">Backslashes in a raw docstring: m\n</span>
</pre></div>
</div>
<p>Otherwise, the backslash will be interpreted as part of the string. For example,
the <code class="docutils literal notranslate"><span class="pre">\n</span></code> above would be interpreted as a newline character. Alternatively, you
can double each backslash in the doctest version (and not use a raw string):</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="n">x</span><span class="p">):</span>
<span class="gp">... </span> <span class="sd">'''Backslashes in a raw docstring: m\\n'''</span>
<span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="vm">__doc__</span><span class="p">)</span>
<span class="go">Backslashes in a raw docstring: m\n</span>
</pre></div>
</div>
</li>
<li><p class="first">The starting column doesn’t matter:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="k">assert</span> <span class="s2">"Easy!"</span>
<span class="go"> >>> import math</span>
<span class="go"> >>> math.floor(1.9)</span>
<span class="go"> 1</span>
</pre></div>
</div>
<p>and as many leading whitespace characters are stripped from the expected output
as appeared in the initial <code class="docutils literal notranslate"><span class="pre">'>>></span> <span class="pre">'</span></code> line that started the example.</p>
</li>
</ul>
</div>
<div class="section" id="what-s-the-execution-context">
<span id="doctest-execution-context"></span><h3>27.3.3.3. What’s the Execution Context?<a class="headerlink" href="#what-s-the-execution-context" title="本標題的永久連結">¶</a></h3>
<p>By default, each time <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> finds a docstring to test, it uses a
<em>shallow copy</em> of <code class="xref py py-mod docutils literal notranslate"><span class="pre">M</span></code>’s globals, so that running tests doesn’t change the
module’s real globals, and so that one test in <code class="xref py py-mod docutils literal notranslate"><span class="pre">M</span></code> can’t leave behind
crumbs that accidentally allow another test to work. This means examples can
freely use any names defined at top-level in <code class="xref py py-mod docutils literal notranslate"><span class="pre">M</span></code>, and names defined earlier
in the docstring being run. Examples cannot see names defined in other
docstrings.</p>
<p>You can force use of your own dict as the execution context by passing
<code class="docutils literal notranslate"><span class="pre">globs=your_dict</span></code> to <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a> or <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a> instead.</p>
</div>
<div class="section" id="what-about-exceptions">
<span id="doctest-exceptions"></span><h3>27.3.3.4. What About Exceptions?<a class="headerlink" href="#what-about-exceptions" title="本標題的永久連結">¶</a></h3>
<p>No problem, provided that the traceback is the only output produced by the
example: just paste in the traceback. <a class="footnote-reference" href="#id2" id="id1">[1]</a> Since tracebacks contain details
that are likely to change rapidly (for example, exact file paths and line
numbers), this is one case where doctest works hard to be flexible in what it
accepts.</p>
<p>Simple example:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">]</span><span class="o">.</span><span class="n">remove</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span>
<span class="gt">Traceback (most recent call last):</span>
File <span class="nb">"<stdin>"</span>, line <span class="m">1</span>, in <span class="n"><module></span>
<span class="gr">ValueError</span>: <span class="n">list.remove(x): x not in list</span>
</pre></div>
</div>
<p>That doctest succeeds if <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> is raised, with the <code class="docutils literal notranslate"><span class="pre">list.remove(x):</span>
<span class="pre">x</span> <span class="pre">not</span> <span class="pre">in</span> <span class="pre">list</span></code> detail as shown.</p>
<p>The expected output for an exception must start with a traceback header, which
may be either of the following two lines, indented the same as the first line of
the example:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">Traceback</span> <span class="p">(</span><span class="n">most</span> <span class="n">recent</span> <span class="n">call</span> <span class="n">last</span><span class="p">):</span>
<span class="n">Traceback</span> <span class="p">(</span><span class="n">innermost</span> <span class="n">last</span><span class="p">):</span>
</pre></div>
</div>
<p>The traceback header is followed by an optional traceback stack, whose contents
are ignored by doctest. The traceback stack is typically omitted, or copied
verbatim from an interactive session.</p>
<p>The traceback stack is followed by the most interesting part: the line(s)
containing the exception type and detail. This is usually the last line of a
traceback, but can extend across multiple lines if the exception has a
multi-line detail:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'multi</span><span class="se">\n</span><span class="s1"> line</span><span class="se">\n</span><span class="s1">detail'</span><span class="p">)</span>
<span class="gt">Traceback (most recent call last):</span>
File <span class="nb">"<stdin>"</span>, line <span class="m">1</span>, in <span class="n"><module></span>
<span class="gr">ValueError</span>: <span class="n">multi</span>
<span class="go"> line</span>
<span class="go">detail</span>
</pre></div>
</div>
<p>The last three lines (starting with <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a>) are compared against the
exception’s type and detail, and the rest are ignored.</p>
<p>Best practice is to omit the traceback stack, unless it adds significant
documentation value to the example. So the last example is probably better as:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'multi</span><span class="se">\n</span><span class="s1"> line</span><span class="se">\n</span><span class="s1">detail'</span><span class="p">)</span>
<span class="gt">Traceback (most recent call last):</span>
<span class="o">...</span>
<span class="gr">ValueError</span>: <span class="n">multi</span>
<span class="go"> line</span>
<span class="go">detail</span>
</pre></div>
</div>
<p>Note that tracebacks are treated very specially. In particular, in the
rewritten example, the use of <code class="docutils literal notranslate"><span class="pre">...</span></code> is independent of doctest’s
<a class="reference internal" href="#doctest.ELLIPSIS" title="doctest.ELLIPSIS"><code class="xref py py-const docutils literal notranslate"><span class="pre">ELLIPSIS</span></code></a> option. The ellipsis in that example could be left out, or
could just as well be three (or three hundred) commas or digits, or an indented
transcript of a Monty Python skit.</p>
<p>Some details you should read once, but won’t need to remember:</p>
<ul>
<li><p class="first">Doctest can’t guess whether your expected output came from an exception
traceback or from ordinary printing. So, e.g., an example that expects
<code class="docutils literal notranslate"><span class="pre">ValueError:</span> <span class="pre">42</span> <span class="pre">is</span> <span class="pre">prime</span></code> will pass whether <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> is actually
raised or if the example merely prints that traceback text. In practice,
ordinary output rarely begins with a traceback header line, so this doesn’t
create real problems.</p>
</li>
<li><p class="first">Each line of the traceback stack (if present) must be indented further than
the first line of the example, <em>or</em> start with a non-alphanumeric character.
The first line following the traceback header indented the same and starting
with an alphanumeric is taken to be the start of the exception detail. Of
course this does the right thing for genuine tracebacks.</p>
</li>
<li><p class="first">When the <a class="reference internal" href="#doctest.IGNORE_EXCEPTION_DETAIL" title="doctest.IGNORE_EXCEPTION_DETAIL"><code class="xref py py-const docutils literal notranslate"><span class="pre">IGNORE_EXCEPTION_DETAIL</span></code></a> doctest option is specified,
everything following the leftmost colon and any module information in the
exception name is ignored.</p>
</li>
<li><p class="first">The interactive shell omits the traceback header line for some
<a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SyntaxError</span></code></a>s. But doctest uses the traceback header line to
distinguish exceptions from non-exceptions. So in the rare case where you need
to test a <a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SyntaxError</span></code></a> that omits the traceback header, you will need to
manually add the traceback header line to your test example.</p>
</li>
<li><p class="first">For some <a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SyntaxError</span></code></a>s, Python displays the character position of the
syntax error, using a <code class="docutils literal notranslate"><span class="pre">^</span></code> marker:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="mi">1</span> <span class="mi">1</span>
File <span class="nb">"<stdin>"</span>, line <span class="m">1</span>
<span class="mi">1</span> <span class="mi">1</span>
<span class="o">^</span>
<span class="gr">SyntaxError</span>: <span class="n">invalid syntax</span>
</pre></div>
</div>
<p>Since the lines showing the position of the error come before the exception type
and detail, they are not checked by doctest. For example, the following test
would pass, even though it puts the <code class="docutils literal notranslate"><span class="pre">^</span></code> marker in the wrong location:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="mi">1</span> <span class="mi">1</span>
File <span class="nb">"<stdin>"</span>, line <span class="m">1</span>
<span class="mi">1</span> <span class="mi">1</span>
<span class="o">^</span>
<span class="gr">SyntaxError</span>: <span class="n">invalid syntax</span>
</pre></div>
</div>
</li>
</ul>
</div>
<div class="section" id="option-flags">
<span id="doctest-options"></span><span id="option-flags-and-directives"></span><h3>27.3.3.5. Option Flags<a class="headerlink" href="#option-flags" title="本標題的永久連結">¶</a></h3>
<p>A number of option flags control various aspects of doctest’s behavior.
Symbolic names for the flags are supplied as module constants, which can be
<a class="reference internal" href="../reference/expressions.html#bitwise"><span class="std std-ref">bitwise ORed</span></a> together and passed to various functions.
The names can also be used in <a class="reference internal" href="#doctest-directives"><span class="std std-ref">doctest directives</span></a>,
and may be passed to the doctest command line interface via the <code class="docutils literal notranslate"><span class="pre">-o</span></code> option.</p>
<div class="versionadded">
<p><span class="versionmodified">3.4 版新加入: </span>The <code class="docutils literal notranslate"><span class="pre">-o</span></code> command line option.</p>
</div>
<p>The first group of options define test semantics, controlling aspects of how
doctest decides whether actual output matches an example’s expected output:</p>
<dl class="data">
<dt id="doctest.DONT_ACCEPT_TRUE_FOR_1">
<code class="descclassname">doctest.</code><code class="descname">DONT_ACCEPT_TRUE_FOR_1</code><a class="headerlink" href="#doctest.DONT_ACCEPT_TRUE_FOR_1" title="本定義的永久連結">¶</a></dt>
<dd><p>By default, if an expected output block contains just <code class="docutils literal notranslate"><span class="pre">1</span></code>, an actual output
block containing just <code class="docutils literal notranslate"><span class="pre">1</span></code> or just <code class="docutils literal notranslate"><span class="pre">True</span></code> is considered to be a match, and
similarly for <code class="docutils literal notranslate"><span class="pre">0</span></code> versus <code class="docutils literal notranslate"><span class="pre">False</span></code>. When <a class="reference internal" href="#doctest.DONT_ACCEPT_TRUE_FOR_1" title="doctest.DONT_ACCEPT_TRUE_FOR_1"><code class="xref py py-const docutils literal notranslate"><span class="pre">DONT_ACCEPT_TRUE_FOR_1</span></code></a> is
specified, neither substitution is allowed. The default behavior caters to that
Python changed the return type of many functions from integer to boolean;
doctests expecting 「little integer」 output still work in these cases. This
option will probably go away, but not for several years.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.DONT_ACCEPT_BLANKLINE">
<code class="descclassname">doctest.</code><code class="descname">DONT_ACCEPT_BLANKLINE</code><a class="headerlink" href="#doctest.DONT_ACCEPT_BLANKLINE" title="本定義的永久連結">¶</a></dt>
<dd><p>By default, if an expected output block contains a line containing only the
string <code class="docutils literal notranslate"><span class="pre"><BLANKLINE></span></code>, then that line will match a blank line in the actual
output. Because a genuinely blank line delimits the expected output, this is
the only way to communicate that a blank line is expected. When
<a class="reference internal" href="#doctest.DONT_ACCEPT_BLANKLINE" title="doctest.DONT_ACCEPT_BLANKLINE"><code class="xref py py-const docutils literal notranslate"><span class="pre">DONT_ACCEPT_BLANKLINE</span></code></a> is specified, this substitution is not allowed.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.NORMALIZE_WHITESPACE">
<code class="descclassname">doctest.</code><code class="descname">NORMALIZE_WHITESPACE</code><a class="headerlink" href="#doctest.NORMALIZE_WHITESPACE" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, all sequences of whitespace (blanks and newlines) are treated as
equal. Any sequence of whitespace within the expected output will match any
sequence of whitespace within the actual output. By default, whitespace must
match exactly. <a class="reference internal" href="#doctest.NORMALIZE_WHITESPACE" title="doctest.NORMALIZE_WHITESPACE"><code class="xref py py-const docutils literal notranslate"><span class="pre">NORMALIZE_WHITESPACE</span></code></a> is especially useful when a line of
expected output is very long, and you want to wrap it across multiple lines in
your source.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.ELLIPSIS">
<code class="descclassname">doctest.</code><code class="descname">ELLIPSIS</code><a class="headerlink" href="#doctest.ELLIPSIS" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, an ellipsis marker (<code class="docutils literal notranslate"><span class="pre">...</span></code>) in the expected output can match
any substring in the actual output. This includes substrings that span line
boundaries, and empty substrings, so it’s best to keep usage of this simple.
Complicated uses can lead to the same kinds of 「oops, it matched too much!」
surprises that <code class="docutils literal notranslate"><span class="pre">.*</span></code> is prone to in regular expressions.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.IGNORE_EXCEPTION_DETAIL">
<code class="descclassname">doctest.</code><code class="descname">IGNORE_EXCEPTION_DETAIL</code><a class="headerlink" href="#doctest.IGNORE_EXCEPTION_DETAIL" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, an example that expects an exception passes if an exception of
the expected type is raised, even if the exception detail does not match. For
example, an example expecting <code class="docutils literal notranslate"><span class="pre">ValueError:</span> <span class="pre">42</span></code> will pass if the actual
exception raised is <code class="docutils literal notranslate"><span class="pre">ValueError:</span> <span class="pre">3*14</span></code>, but will fail, e.g., if
<a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> is raised.</p>
<p>It will also ignore the module name used in Python 3 doctest reports. Hence
both of these variations will work with the flag specified, regardless of
whether the test is run under Python 2.7 or Python 3.2 (or later versions):</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="k">raise</span> <span class="n">CustomError</span><span class="p">(</span><span class="s1">'message'</span><span class="p">)</span>
<span class="gt">Traceback (most recent call last):</span>
<span class="gr">CustomError</span>: <span class="n">message</span>
<span class="gp">>>> </span><span class="k">raise</span> <span class="n">CustomError</span><span class="p">(</span><span class="s1">'message'</span><span class="p">)</span>
<span class="gt">Traceback (most recent call last):</span>
<span class="gr">my_module.CustomError</span>: <span class="n">message</span>
</pre></div>
</div>
<p>Note that <a class="reference internal" href="#doctest.ELLIPSIS" title="doctest.ELLIPSIS"><code class="xref py py-const docutils literal notranslate"><span class="pre">ELLIPSIS</span></code></a> can also be used to ignore the
details of the exception message, but such a test may still fail based
on whether or not the module details are printed as part of the
exception name. Using <a class="reference internal" href="#doctest.IGNORE_EXCEPTION_DETAIL" title="doctest.IGNORE_EXCEPTION_DETAIL"><code class="xref py py-const docutils literal notranslate"><span class="pre">IGNORE_EXCEPTION_DETAIL</span></code></a> and the details
from Python 2.3 is also the only clear way to write a doctest that doesn’t
care about the exception detail yet continues to pass under Python 2.3 or
earlier (those releases do not support <a class="reference internal" href="#doctest-directives"><span class="std std-ref">doctest directives</span></a> and ignore them as irrelevant comments). For example:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">)[</span><span class="mi">3</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'moo'</span>
<span class="gt">Traceback (most recent call last):</span>
File <span class="nb">"<stdin>"</span>, line <span class="m">1</span>, in <span class="n"><module></span>
<span class="gr">TypeError</span>: <span class="n">object doesn't support item assignment</span>
</pre></div>
</div>
<p>passes under Python 2.3 and later Python versions with the flag specified,
even though the detail
changed in Python 2.4 to say 「does not」 instead of 「doesn’t」.</p>
<div class="versionchanged">
<p><span class="versionmodified">3.2 版更變: </span><a class="reference internal" href="#doctest.IGNORE_EXCEPTION_DETAIL" title="doctest.IGNORE_EXCEPTION_DETAIL"><code class="xref py py-const docutils literal notranslate"><span class="pre">IGNORE_EXCEPTION_DETAIL</span></code></a> now also ignores any information relating
to the module containing the exception under test.</p>
</div>
</dd></dl>
<dl class="data">
<dt id="doctest.SKIP">
<code class="descclassname">doctest.</code><code class="descname">SKIP</code><a class="headerlink" href="#doctest.SKIP" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, do not run the example at all. This can be useful in contexts
where doctest examples serve as both documentation and test cases, and an
example should be included for documentation purposes, but should not be
checked. E.g., the example’s output might be random; or the example might
depend on resources which would be unavailable to the test driver.</p>
<p>The SKIP flag can also be used for temporarily 「commenting out」 examples.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.COMPARISON_FLAGS">
<code class="descclassname">doctest.</code><code class="descname">COMPARISON_FLAGS</code><a class="headerlink" href="#doctest.COMPARISON_FLAGS" title="本定義的永久連結">¶</a></dt>
<dd><p>A bitmask or’ing together all the comparison flags above.</p>
</dd></dl>
<p>The second group of options controls how test failures are reported:</p>
<dl class="data">
<dt id="doctest.REPORT_UDIFF">
<code class="descclassname">doctest.</code><code class="descname">REPORT_UDIFF</code><a class="headerlink" href="#doctest.REPORT_UDIFF" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, failures that involve multi-line expected and actual outputs are
displayed using a unified diff.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.REPORT_CDIFF">
<code class="descclassname">doctest.</code><code class="descname">REPORT_CDIFF</code><a class="headerlink" href="#doctest.REPORT_CDIFF" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, failures that involve multi-line expected and actual outputs
will be displayed using a context diff.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.REPORT_NDIFF">
<code class="descclassname">doctest.</code><code class="descname">REPORT_NDIFF</code><a class="headerlink" href="#doctest.REPORT_NDIFF" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, differences are computed by <code class="docutils literal notranslate"><span class="pre">difflib.Differ</span></code>, using the same
algorithm as the popular <code class="file docutils literal notranslate"><span class="pre">ndiff.py</span></code> utility. This is the only method that
marks differences within lines as well as across lines. For example, if a line
of expected output contains digit <code class="docutils literal notranslate"><span class="pre">1</span></code> where actual output contains letter
<code class="docutils literal notranslate"><span class="pre">l</span></code>, a line is inserted with a caret marking the mismatching column positions.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.REPORT_ONLY_FIRST_FAILURE">
<code class="descclassname">doctest.</code><code class="descname">REPORT_ONLY_FIRST_FAILURE</code><a class="headerlink" href="#doctest.REPORT_ONLY_FIRST_FAILURE" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, display the first failing example in each doctest, but suppress
output for all remaining examples. This will prevent doctest from reporting
correct examples that break because of earlier failures; but it might also hide
incorrect examples that fail independently of the first failure. When
<a class="reference internal" href="#doctest.REPORT_ONLY_FIRST_FAILURE" title="doctest.REPORT_ONLY_FIRST_FAILURE"><code class="xref py py-const docutils literal notranslate"><span class="pre">REPORT_ONLY_FIRST_FAILURE</span></code></a> is specified, the remaining examples are
still run, and still count towards the total number of failures reported; only
the output is suppressed.</p>
</dd></dl>
<dl class="data">
<dt id="doctest.FAIL_FAST">
<code class="descclassname">doctest.</code><code class="descname">FAIL_FAST</code><a class="headerlink" href="#doctest.FAIL_FAST" title="本定義的永久連結">¶</a></dt>
<dd><p>When specified, exit after the first failing example and don’t attempt to run
the remaining examples. Thus, the number of failures reported will be at most
1. This flag may be useful during debugging, since examples after the first
failure won’t even produce debugging output.</p>
<p>The doctest command line accepts the option <code class="docutils literal notranslate"><span class="pre">-f</span></code> as a shorthand for <code class="docutils literal notranslate"><span class="pre">-o</span>
<span class="pre">FAIL_FAST</span></code>.</p>
<div class="versionadded">
<p><span class="versionmodified">3.4 版新加入.</span></p>
</div>
</dd></dl>
<dl class="data">
<dt id="doctest.REPORTING_FLAGS">
<code class="descclassname">doctest.</code><code class="descname">REPORTING_FLAGS</code><a class="headerlink" href="#doctest.REPORTING_FLAGS" title="本定義的永久連結">¶</a></dt>
<dd><p>A bitmask or’ing together all the reporting flags above.</p>
</dd></dl>
<p>There is also a way to register new option flag names, though this isn’t
useful unless you intend to extend <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> internals via subclassing:</p>
<dl class="function">
<dt id="doctest.register_optionflag">
<code class="descclassname">doctest.</code><code class="descname">register_optionflag</code><span class="sig-paren">(</span><em>name</em><span class="sig-paren">)</span><a class="headerlink" href="#doctest.register_optionflag" title="本定義的永久連結">¶</a></dt>
<dd><p>Create a new option flag with a given name, and return the new flag’s integer
value. <a class="reference internal" href="#doctest.register_optionflag" title="doctest.register_optionflag"><code class="xref py py-func docutils literal notranslate"><span class="pre">register_optionflag()</span></code></a> can be used when subclassing
<a class="reference internal" href="#doctest.OutputChecker" title="doctest.OutputChecker"><code class="xref py py-class docutils literal notranslate"><span class="pre">OutputChecker</span></code></a> or <a class="reference internal" href="#doctest.DocTestRunner" title="doctest.DocTestRunner"><code class="xref py py-class docutils literal notranslate"><span class="pre">DocTestRunner</span></code></a> to create new options that are
supported by your subclasses. <a class="reference internal" href="#doctest.register_optionflag" title="doctest.register_optionflag"><code class="xref py py-func docutils literal notranslate"><span class="pre">register_optionflag()</span></code></a> should always be
called using the following idiom:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">MY_FLAG</span> <span class="o">=</span> <span class="n">register_optionflag</span><span class="p">(</span><span class="s1">'MY_FLAG'</span><span class="p">)</span>
</pre></div>
</div>
</dd></dl>
</div>
<div class="section" id="directives">
<span id="doctest-directives"></span><h3>27.3.3.6. Directives<a class="headerlink" href="#directives" title="本標題的永久連結">¶</a></h3>
<p>Doctest directives may be used to modify the <a class="reference internal" href="#doctest-options"><span class="std std-ref">option flags</span></a> for an individual example. Doctest directives are
special Python comments following an example’s source code:</p>
<pre>
<strong id="grammar-token-directive">directive </strong> ::= "#" "doctest:" <a class="reference internal" href="#grammar-token-directive_options"><code class="xref docutils literal notranslate"><span class="pre">directive_options</span></code></a>
<strong id="grammar-token-directive_options">directive_options </strong> ::= <a class="reference internal" href="#grammar-token-directive_option"><code class="xref docutils literal notranslate"><span class="pre">directive_option</span></code></a> ("," <a class="reference internal" href="#grammar-token-directive_option"><code class="xref docutils literal notranslate"><span class="pre">directive_option</span></code></a>)\*
<strong id="grammar-token-directive_option">directive_option </strong> ::= <a class="reference internal" href="#grammar-token-on_or_off"><code class="xref docutils literal notranslate"><span class="pre">on_or_off</span></code></a> <a class="reference internal" href="#grammar-token-directive_option_name"><code class="xref docutils literal notranslate"><span class="pre">directive_option_name</span></code></a>
<strong id="grammar-token-on_or_off">on_or_off </strong> ::= "+" \| "-"
<strong id="grammar-token-directive_option_name">directive_option_name</strong> ::= "DONT_ACCEPT_BLANKLINE" \| "NORMALIZE_WHITESPACE" \| ...
</pre>
<p>Whitespace is not allowed between the <code class="docutils literal notranslate"><span class="pre">+</span></code> or <code class="docutils literal notranslate"><span class="pre">-</span></code> and the directive option
name. The directive option name can be any of the option flag names explained
above.</p>
<p>An example’s doctest directives modify doctest’s behavior for that single
example. Use <code class="docutils literal notranslate"><span class="pre">+</span></code> to enable the named behavior, or <code class="docutils literal notranslate"><span class="pre">-</span></code> to disable it.</p>
<p>For example, this test passes:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">20</span><span class="p">)))</span> <span class="c1"># doctest: +NORMALIZE_WHITESPACE</span>
<span class="go">[0, 1, 2, 3, 4, 5, 6, 7, 8, 9,</span>
<span class="go">10, 11, 12, 13, 14, 15, 16, 17, 18, 19]</span>
</pre></div>
</div>
<p>Without the directive it would fail, both because the actual output doesn’t have
two blanks before the single-digit list elements, and because the actual output
is on a single line. This test also passes, and also requires a directive to do
so:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">20</span><span class="p">)))</span> <span class="c1"># doctest: +ELLIPSIS</span>
<span class="go">[0, 1, ..., 18, 19]</span>
</pre></div>
</div>
<p>Multiple directives can be used on a single physical line, separated by
commas:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">20</span><span class="p">)))</span> <span class="c1"># doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE</span>
<span class="go">[0, 1, ..., 18, 19]</span>
</pre></div>
</div>
<p>If multiple directive comments are used for a single example, then they are
combined:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">20</span><span class="p">)))</span> <span class="c1"># doctest: +ELLIPSIS</span>
<span class="gp">... </span> <span class="c1"># doctest: +NORMALIZE_WHITESPACE</span>
<span class="go">[0, 1, ..., 18, 19]</span>
</pre></div>
</div>
<p>As the previous example shows, you can add <code class="docutils literal notranslate"><span class="pre">...</span></code> lines to your example
containing only directives. This can be useful when an example is too long for
a directive to comfortably fit on the same line:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">5</span><span class="p">))</span> <span class="o">+</span> <span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">))</span> <span class="o">+</span> <span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">30</span><span class="p">,</span> <span class="mi">40</span><span class="p">)))</span>
<span class="gp">... </span><span class="c1"># doctest: +ELLIPSIS</span>
<span class="go">[0, ..., 4, 10, ..., 19, 30, ..., 39]</span>
</pre></div>
</div>
<p>Note that since all options are disabled by default, and directives apply only
to the example they appear in, enabling options (via <code class="docutils literal notranslate"><span class="pre">+</span></code> in a directive) is
usually the only meaningful choice. However, option flags can also be passed to
functions that run doctests, establishing different defaults. In such cases,
disabling an option via <code class="docutils literal notranslate"><span class="pre">-</span></code> in a directive can be useful.</p>
</div>
<div class="section" id="warnings">
<span id="doctest-warnings"></span><h3>27.3.3.7. Warnings<a class="headerlink" href="#warnings" title="本標題的永久連結">¶</a></h3>
<p><a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> is serious about requiring exact matches in expected output. If
even a single character doesn’t match, the test fails. This will probably
surprise you a few times, as you learn exactly what Python does and doesn’t
guarantee about output. For example, when printing a dict, Python doesn’t
guarantee that the key-value pairs will be printed in any particular order, so a
test like</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">foo</span><span class="p">()</span>
<span class="go">{"Hermione": "hippogryph", "Harry": "broomstick"}</span>
</pre></div>
</div>
<p>is vulnerable! One workaround is to do</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">foo</span><span class="p">()</span> <span class="o">==</span> <span class="p">{</span><span class="s2">"Hermione"</span><span class="p">:</span> <span class="s2">"hippogryph"</span><span class="p">,</span> <span class="s2">"Harry"</span><span class="p">:</span> <span class="s2">"broomstick"</span><span class="p">}</span>
<span class="go">True</span>
</pre></div>
</div>
<p>instead. Another is to do</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">d</span> <span class="o">=</span> <span class="nb">sorted</span><span class="p">(</span><span class="n">foo</span><span class="p">()</span><span class="o">.</span><span class="n">items</span><span class="p">())</span>
<span class="gp">>>> </span><span class="n">d</span>
<span class="go">[('Harry', 'broomstick'), ('Hermione', 'hippogryph')]</span>
</pre></div>
</div>
<p>There are others, but you get the idea.</p>
<p>Another bad idea is to print things that embed an object address, like</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">id</span><span class="p">(</span><span class="mf">1.0</span><span class="p">)</span> <span class="c1"># certain to fail some of the time</span>
<span class="go">7948648</span>
<span class="gp">>>> </span><span class="k">class</span> <span class="nc">C</span><span class="p">:</span> <span class="k">pass</span>
<span class="gp">>>> </span><span class="n">C</span><span class="p">()</span> <span class="c1"># the default repr() for instances embeds an address</span>
<span class="go"><__main__.C instance at 0x00AC18F0></span>
</pre></div>
</div>
<p>The <a class="reference internal" href="#doctest.ELLIPSIS" title="doctest.ELLIPSIS"><code class="xref py py-const docutils literal notranslate"><span class="pre">ELLIPSIS</span></code></a> directive gives a nice approach for the last example:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">C</span><span class="p">()</span> <span class="c1">#doctest: +ELLIPSIS</span>
<span class="go"><__main__.C instance at 0x...></span>
</pre></div>
</div>
<p>Floating-point numbers are also subject to small output variations across
platforms, because Python defers to the platform C library for float formatting,
and C libraries vary widely in quality here.</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="mf">1.</span><span class="o">/</span><span class="mi">7</span> <span class="c1"># risky</span>
<span class="go">0.14285714285714285</span>
<span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="mf">1.</span><span class="o">/</span><span class="mi">7</span><span class="p">)</span> <span class="c1"># safer</span>
<span class="go">0.142857142857</span>
<span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="nb">round</span><span class="p">(</span><span class="mf">1.</span><span class="o">/</span><span class="mi">7</span><span class="p">,</span> <span class="mi">6</span><span class="p">))</span> <span class="c1"># much safer</span>
<span class="go">0.142857</span>
</pre></div>
</div>
<p>Numbers of the form <code class="docutils literal notranslate"><span class="pre">I/2.**J</span></code> are safe across all platforms, and I often
contrive doctest examples to produce numbers of that form:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="mf">3.</span><span class="o">/</span><span class="mi">4</span> <span class="c1"># utterly safe</span>
<span class="go">0.75</span>
</pre></div>
</div>
<p>Simple fractions are also easier for people to understand, and that makes for
better documentation.</p>
</div>
</div>
<div class="section" id="basic-api">
<span id="doctest-basic-api"></span><h2>27.3.4. Basic API<a class="headerlink" href="#basic-api" title="本標題的永久連結">¶</a></h2>
<p>The functions <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a> and <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a> provide a simple interface to
doctest that should be sufficient for most basic uses. For a less formal
introduction to these two functions, see sections <a class="reference internal" href="#doctest-simple-testmod"><span class="std std-ref">Simple Usage: Checking Examples in Docstrings</span></a>
and <a class="reference internal" href="#doctest-simple-testfile"><span class="std std-ref">Simple Usage: Checking Examples in a Text File</span></a>.</p>
<dl class="function">
<dt id="doctest.testfile">
<code class="descclassname">doctest.</code><code class="descname">testfile</code><span class="sig-paren">(</span><em>filename</em>, <em>module_relative=True</em>, <em>name=None</em>, <em>package=None</em>, <em>globs=None</em>, <em>verbose=None</em>, <em>report=True</em>, <em>optionflags=0</em>, <em>extraglobs=None</em>, <em>raise_on_error=False</em>, <em>parser=DocTestParser()</em>, <em>encoding=None</em><span class="sig-paren">)</span><a class="headerlink" href="#doctest.testfile" title="本定義的永久連結">¶</a></dt>
<dd><p>All arguments except <em>filename</em> are optional, and should be specified in keyword
form.</p>
<p>Test examples in the file named <em>filename</em>. Return <code class="docutils literal notranslate"><span class="pre">(failure_count,</span>
<span class="pre">test_count)</span></code>.</p>
<p>Optional argument <em>module_relative</em> specifies how the filename should be
interpreted:</p>
<ul class="simple">
<li>If <em>module_relative</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code> (the default), then <em>filename</em> specifies an
OS-independent module-relative path. By default, this path is relative to the
calling module’s directory; but if the <em>package</em> argument is specified, then it
is relative to that package. To ensure OS-independence, <em>filename</em> should use
<code class="docutils literal notranslate"><span class="pre">/</span></code> characters to separate path segments, and may not be an absolute path
(i.e., it may not begin with <code class="docutils literal notranslate"><span class="pre">/</span></code>).</li>
<li>If <em>module_relative</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code>, then <em>filename</em> specifies an OS-specific
path. The path may be absolute or relative; relative paths are resolved with
respect to the current working directory.</li>
</ul>
<p>Optional argument <em>name</em> gives the name of the test; by default, or if <code class="docutils literal notranslate"><span class="pre">None</span></code>,
<code class="docutils literal notranslate"><span class="pre">os.path.basename(filename)</span></code> is used.</p>
<p>Optional argument <em>package</em> is a Python package or the name of a Python package
whose directory should be used as the base directory for a module-relative
filename. If no package is specified, then the calling module’s directory is
used as the base directory for module-relative filenames. It is an error to
specify <em>package</em> if <em>module_relative</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code>.</p>
<p>Optional argument <em>globs</em> gives a dict to be used as the globals when executing
examples. A new shallow copy of this dict is created for the doctest, so its
examples start with a clean slate. By default, or if <code class="docutils literal notranslate"><span class="pre">None</span></code>, a new empty dict
is used.</p>
<p>Optional argument <em>extraglobs</em> gives a dict merged into the globals used to
execute examples. This works like <a class="reference internal" href="stdtypes.html#dict.update" title="dict.update"><code class="xref py py-meth docutils literal notranslate"><span class="pre">dict.update()</span></code></a>: if <em>globs</em> and
<em>extraglobs</em> have a common key, the associated value in <em>extraglobs</em> appears in
the combined dict. By default, or if <code class="docutils literal notranslate"><span class="pre">None</span></code>, no extra globals are used. This
is an advanced feature that allows parameterization of doctests. For example, a
doctest can be written for a base class, using a generic name for the class,
then reused to test any number of subclasses by passing an <em>extraglobs</em> dict
mapping the generic name to the subclass to be tested.</p>
<p>Optional argument <em>verbose</em> prints lots of stuff if true, and prints only
failures if false; by default, or if <code class="docutils literal notranslate"><span class="pre">None</span></code>, it’s true if and only if <code class="docutils literal notranslate"><span class="pre">'-v'</span></code>
is in <code class="docutils literal notranslate"><span class="pre">sys.argv</span></code>.</p>
<p>Optional argument <em>report</em> prints a summary at the end when true, else prints
nothing at the end. In verbose mode, the summary is detailed, else the summary
is very brief (in fact, empty if all tests passed).</p>
<p>Optional argument <em>optionflags</em> (default value 0) takes the
<a class="reference internal" href="../reference/expressions.html#bitwise"><span class="std std-ref">bitwise OR</span></a> of option flags.
See section <a class="reference internal" href="#doctest-options"><span class="std std-ref">Option Flags</span></a>.</p>
<p>Optional argument <em>raise_on_error</em> defaults to false. If true, an exception is
raised upon the first failure or unexpected exception in an example. This
allows failures to be post-mortem debugged. Default behavior is to continue
running examples.</p>
<p>Optional argument <em>parser</em> specifies a <a class="reference internal" href="#doctest.DocTestParser" title="doctest.DocTestParser"><code class="xref py py-class docutils literal notranslate"><span class="pre">DocTestParser</span></code></a> (or subclass) that
should be used to extract tests from the files. It defaults to a normal parser
(i.e., <code class="docutils literal notranslate"><span class="pre">DocTestParser()</span></code>).</p>
<p>Optional argument <em>encoding</em> specifies an encoding that should be used to
convert the file to unicode.</p>
</dd></dl>
<dl class="function">
<dt id="doctest.testmod">
<code class="descclassname">doctest.</code><code class="descname">testmod</code><span class="sig-paren">(</span><em>m=None</em>, <em>name=None</em>, <em>globs=None</em>, <em>verbose=None</em>, <em>report=True</em>, <em>optionflags=0</em>, <em>extraglobs=None</em>, <em>raise_on_error=False</em>, <em>exclude_empty=False</em><span class="sig-paren">)</span><a class="headerlink" href="#doctest.testmod" title="本定義的永久連結">¶</a></dt>
<dd><p>All arguments are optional, and all except for <em>m</em> should be specified in
keyword form.</p>
<p>Test examples in docstrings in functions and classes reachable from module <em>m</em>
(or module <a class="reference internal" href="__main__.html#module-__main__" title="__main__: The environment where the top-level script is run."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a> if <em>m</em> is not supplied or is <code class="docutils literal notranslate"><span class="pre">None</span></code>), starting with
<code class="docutils literal notranslate"><span class="pre">m.__doc__</span></code>.</p>
<p>Also test examples reachable from dict <code class="docutils literal notranslate"><span class="pre">m.__test__</span></code>, if it exists and is not
<code class="docutils literal notranslate"><span class="pre">None</span></code>. <code class="docutils literal notranslate"><span class="pre">m.__test__</span></code> maps names (strings) to functions, classes and
strings; function and class docstrings are searched for examples; strings are
searched directly, as if they were docstrings.</p>
<p>Only docstrings attached to objects belonging to module <em>m</em> are searched.</p>
<p>Return <code class="docutils literal notranslate"><span class="pre">(failure_count,</span> <span class="pre">test_count)</span></code>.</p>
<p>Optional argument <em>name</em> gives the name of the module; by default, or if
<code class="docutils literal notranslate"><span class="pre">None</span></code>, <code class="docutils literal notranslate"><span class="pre">m.__name__</span></code> is used.</p>
<p>Optional argument <em>exclude_empty</em> defaults to false. If true, objects for which
no doctests are found are excluded from consideration. The default is a backward
compatibility hack, so that code still using <code class="xref py py-meth docutils literal notranslate"><span class="pre">doctest.master.summarize()</span></code> in
conjunction with <a class="reference internal" href="#doctest.testmod" title="doctest.testmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">testmod()</span></code></a> continues to get output for objects with no
tests. The <em>exclude_empty</em> argument to the newer <a class="reference internal" href="#doctest.DocTestFinder" title="doctest.DocTestFinder"><code class="xref py py-class docutils literal notranslate"><span class="pre">DocTestFinder</span></code></a>
constructor defaults to true.</p>
<p>Optional arguments <em>extraglobs</em>, <em>verbose</em>, <em>report</em>, <em>optionflags</em>,
<em>raise_on_error</em>, and <em>globs</em> are the same as for function <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a>
above, except that <em>globs</em> defaults to <code class="docutils literal notranslate"><span class="pre">m.__dict__</span></code>.</p>
</dd></dl>
<dl class="function">
<dt id="doctest.run_docstring_examples">
<code class="descclassname">doctest.</code><code class="descname">run_docstring_examples</code><span class="sig-paren">(</span><em>f</em>, <em>globs</em>, <em>verbose=False</em>, <em>name="NoName"</em>, <em>compileflags=None</em>, <em>optionflags=0</em><span class="sig-paren">)</span><a class="headerlink" href="#doctest.run_docstring_examples" title="本定義的永久連結">¶</a></dt>
<dd><p>Test examples associated with object <em>f</em>; for example, <em>f</em> may be a string,
a module, a function, or a class object.</p>
<p>A shallow copy of dictionary argument <em>globs</em> is used for the execution context.</p>
<p>Optional argument <em>name</em> is used in failure messages, and defaults to
<code class="docutils literal notranslate"><span class="pre">"NoName"</span></code>.</p>
<p>If optional argument <em>verbose</em> is true, output is generated even if there are no
failures. By default, output is generated only in case of an example failure.</p>
<p>Optional argument <em>compileflags</em> gives the set of flags that should be used by
the Python compiler when running the examples. By default, or if <code class="docutils literal notranslate"><span class="pre">None</span></code>,
flags are deduced corresponding to the set of future features found in <em>globs</em>.</p>
<p>Optional argument <em>optionflags</em> works as for function <a class="reference internal" href="#doctest.testfile" title="doctest.testfile"><code class="xref py py-func docutils literal notranslate"><span class="pre">testfile()</span></code></a> above.</p>
</dd></dl>
</div>
<div class="section" id="unittest-api">
<span id="doctest-unittest-api"></span><h2>27.3.5. Unittest API<a class="headerlink" href="#unittest-api" title="本標題的永久連結">¶</a></h2>
<p>As your collection of doctest’ed modules grows, you’ll want a way to run all
their doctests systematically. <a class="reference internal" href="#module-doctest" title="doctest: Test pieces of code within docstrings."><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code></a> provides two functions that can
be used to create <a class="reference internal" href="unittest.html#module-unittest" title="unittest: Unit testing framework for Python."><code class="xref py py-mod docutils literal notranslate"><span class="pre">unittest</span></code></a> test suites from modules and text files
containing doctests. To integrate with <a class="reference internal" href="unittest.html#module-unittest" title="unittest: Unit testing framework for Python."><code class="xref py py-mod docutils literal notranslate"><span class="pre">unittest</span></code></a> test discovery, include
a <code class="xref py py-func docutils literal notranslate"><span class="pre">load_tests()</span></code> function in your test module:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">unittest</span>
<span class="kn">import</span> <span class="nn">doctest</span>
<span class="kn">import</span> <span class="nn">my_module_with_doctests</span>
<span class="k">def</span> <span class="nf">load_tests</span><span class="p">(</span><span class="n">loader</span><span class="p">,</span> <span class="n">tests</span><span class="p">,</span> <span class="n">ignore</span><span class="p">):</span>
<span class="n">tests</span><span class="o">.</span><span class="n">addTests</span><span class="p">(</span><span class="n">doctest</span><span class="o">.</span><span class="n">DocTestSuite</span><span class="p">(</span><span class="n">my_module_with_doctests</span><span class="p">))</span>
<span class="k">return</span> <span class="n">tests</span>
</pre></div>
</div>
<p>There are two main functions for creating <a class="reference internal" href="unittest.html#unittest.TestSuite" title="unittest.TestSuite"><code class="xref py py-class docutils literal notranslate"><span class="pre">unittest.TestSuite</span></code></a> instances
from text files and modules with doctests:</p>
<dl class="function">
<dt id="doctest.DocFileSuite">
<code class="descclassname">doctest.</code><code class="descname">DocFileSuite</code><span class="sig-paren">(</span><em>*paths</em>, <em>module_relative=True</em>, <em>package=None</em>, <em>setUp=None</em>, <em>tearDown=None</em>, <em>globs=None</em>, <em>optionflags=0</em>, <em>parser=DocTestParser()</em>, <em>encoding=None</em><span class="sig-paren">)</span><a class="headerlink" href="#doctest.DocFileSuite" title="本定義的永久連結">¶</a></dt>
<dd><p>Convert doctest tests from one or more text files to a
<a class="reference internal" href="unittest.html#unittest.TestSuite" title="unittest.TestSuite"><code class="xref py py-class docutils literal notranslate"><span class="pre">unittest.TestSuite</span></code></a>.</p>
<p>The returned <a class="reference internal" href="unittest.html#unittest.TestSuite" title="unittest.TestSuite"><code class="xref py py-class docutils literal notranslate"><span class="pre">unittest.TestSuite</span></code></a> is to be run by the unittest framework
and runs the interactive examples in each file. If an example in any file
fails, then the synthesized unit test fails, and a <code class="xref py py-exc docutils literal notranslate"><span class="pre">failureException</span></code>
exception is raised showing the name of the file containing the test and a
(sometimes approximate) line number.</p>
<p>Pass one or more paths (as strings) to text files to be examined.</p>
<p>Options may be provided as keyword arguments:</p>
<p>Optional argument <em>module_relative</em> specifies how the filenames in <em>paths</em>
should be interpreted:</p>
<ul class="simple">
<li>If <em>module_relative</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code> (the default), then each filename in
<em>paths</em> specifies an OS-independent module-relative path. By default, this
path is relative to the calling module’s directory; but if the <em>package</em>
argument is specified, then it is relative to that package. To ensure
OS-independence, each filename should use <code class="docutils literal notranslate"><span class="pre">/</span></code> characters to separate path
segments, and may not be an absolute path (i.e., it may not begin with
<code class="docutils literal notranslate"><span class="pre">/</span></code>).</li>
<li>If <em>module_relative</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code>, then each filename in <em>paths</em> specifies
an OS-specific path. The path may be absolute or relative; relative paths
are resolved with respect to the current working directory.</li>
</ul>
<p>Optional argument <em>package</em> is a Python package or the name of a Python
package whose directory should be used as the base directory for
module-relative filenames in <em>paths</em>. If no package is specified, then the
calling module’s directory is used as the base directory for module-relative
filenames. It is an error to specify <em>package</em> if <em>module_relative</em> is
<code class="docutils literal notranslate"><span class="pre">False</span></code>.</p>
<p>Optional argument <em>setUp</em> specifies a set-up function for the test suite.
This is called before running the tests in each file. The <em>setUp</em> function
will be passed a <a class="reference internal" href="#doctest.DocTest" title="doctest.DocTest"><code class="xref py py-class docutils literal notranslate"><span class="pre">DocTest</span></code></a> object. The setUp function can access the
test globals as the <em>globs</em> attribute of the test passed.</p>
<p>Optional argument <em>tearDown</em> specifies a tear-down function for the test
suite. This is called after running the tests in each file. The <em>tearDown</em>
function will be passed a <a class="reference internal" href="#doctest.DocTest" title="doctest.DocTest"><code class="xref py py-class docutils literal notranslate"><span class="pre">DocTest</span></code></a> object. The setUp function can
access the test globals as the <em>globs</em> attribute of the test passed.</p>
<p>Optional argument <em>globs</em> is a dictionary containing the initial global
variables for the tests. A new copy of this dictionary is created for each
test. By default, <em>globs</em> is a new empty dictionary.</p>
<p>Optional argument <em>optionflags</em> specifies the default doctest options for the
tests, created by or-ing together individual option flags. See section
<a class="reference internal" href="#doctest-options"><span class="std std-ref">Option Flags</span></a>. See function <a class="reference internal" href="#doctest.set_unittest_reportflags" title="doctest.set_unittest_reportflags"><code class="xref py py-func docutils literal notranslate"><span class="pre">set_unittest_reportflags()</span></code></a> below
for a better way to set reporting options.</p>
<p>Optional argument <em>parser</em> specifies a <a class="reference internal" href="#doctest.DocTestParser" title="doctest.DocTestParser"><code class="xref py py-class docutils literal notranslate"><span class="pre">DocTestParser</span></code></a> (or subclass)
that should be used to extract tests from the files. It defaults to a normal
parser (i.e., <code class="docutils literal notranslate"><span class="pre">DocTestParser()</span></code>).</p>