<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8" /> <title>Development Tools — Python 3.7.4 documentation</title> <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/language_data.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 3.7.4 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="typing — Support for type hints" href="typing.html" /> <link rel="prev" title="Other Graphical User Interface Packages" href="othergui.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/library/development.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> <script type="text/javascript" src="../_static/switchers.js"></script> <style> @media only screen { table.full-width-table { width: 100%; } } </style> </head><body> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="typing.html" title="typing — Support for type hints" accesskey="N">next</a> |</li> <li class="right" > <a href="othergui.html" title="Other Graphical User Interface Packages" accesskey="P">previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <span class="language_switcher_placeholder">en</span> <span class="version_switcher_placeholder">3.7.4</span> <a href="../index.html">Documentation </a> » </li> <li class="nav-item nav-item-1"><a href="index.html" accesskey="U">The Python Standard Library</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="development-tools"> <span id="development"></span><h1>Development Tools<a class="headerlink" href="#development-tools" title="Permalink to this headline">¶</a></h1> <p>The modules described in this chapter help you write software. For example, the <a class="reference internal" href="pydoc.html#module-pydoc" title="pydoc: Documentation generator and online help system."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pydoc</span></code></a> module takes a module and generates documentation based on the module’s contents. The <a class="reference internal" href="doctest.html#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> and <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> modules contains frameworks for writing unit tests that automatically exercise code and verify that the expected output is produced. <strong class="program">2to3</strong> can translate Python 2.x source code into valid Python 3.x code.</p> <p>The list of modules described in this chapter is:</p> <div class="toctree-wrapper compound"> <ul> <li class="toctree-l1"><a class="reference internal" href="typing.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">typing</span></code> — Support for type hints</a><ul> <li class="toctree-l2"><a class="reference internal" href="typing.html#type-aliases">Type aliases</a></li> <li class="toctree-l2"><a class="reference internal" href="typing.html#newtype">NewType</a></li> <li class="toctree-l2"><a class="reference internal" href="typing.html#callable">Callable</a></li> <li class="toctree-l2"><a class="reference internal" href="typing.html#generics">Generics</a></li> <li class="toctree-l2"><a class="reference internal" href="typing.html#user-defined-generic-types">User-defined generic types</a></li> <li class="toctree-l2"><a class="reference internal" href="typing.html#the-any-type">The <code class="xref py py-data docutils literal notranslate"><span class="pre">Any</span></code> type</a></li> <li class="toctree-l2"><a class="reference internal" href="typing.html#classes-functions-and-decorators">Classes, functions, and decorators</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="pydoc.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">pydoc</span></code> — Documentation generator and online help system</a></li> <li class="toctree-l1"><a class="reference internal" href="doctest.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">doctest</span></code> — Test interactive Python examples</a><ul> <li class="toctree-l2"><a class="reference internal" href="doctest.html#simple-usage-checking-examples-in-docstrings">Simple Usage: Checking Examples in Docstrings</a></li> <li class="toctree-l2"><a class="reference internal" href="doctest.html#simple-usage-checking-examples-in-a-text-file">Simple Usage: Checking Examples in a Text File</a></li> <li class="toctree-l2"><a class="reference internal" href="doctest.html#how-it-works">How It Works</a><ul> <li class="toctree-l3"><a class="reference internal" href="doctest.html#which-docstrings-are-examined">Which Docstrings Are Examined?</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#how-are-docstring-examples-recognized">How are Docstring Examples Recognized?</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#what-s-the-execution-context">What’s the Execution Context?</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#what-about-exceptions">What About Exceptions?</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#option-flags">Option Flags</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#directives">Directives</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#warnings">Warnings</a></li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="doctest.html#basic-api">Basic API</a></li> <li class="toctree-l2"><a class="reference internal" href="doctest.html#unittest-api">Unittest API</a></li> <li class="toctree-l2"><a class="reference internal" href="doctest.html#advanced-api">Advanced API</a><ul> <li class="toctree-l3"><a class="reference internal" href="doctest.html#doctest-objects">DocTest Objects</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#example-objects">Example Objects</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#doctestfinder-objects">DocTestFinder objects</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#doctestparser-objects">DocTestParser objects</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#doctestrunner-objects">DocTestRunner objects</a></li> <li class="toctree-l3"><a class="reference internal" href="doctest.html#outputchecker-objects">OutputChecker objects</a></li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="doctest.html#debugging">Debugging</a></li> <li class="toctree-l2"><a class="reference internal" href="doctest.html#soapbox">Soapbox</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="unittest.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">unittest</span></code> — Unit testing framework</a><ul> <li class="toctree-l2"><a class="reference internal" href="unittest.html#basic-example">Basic example</a></li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#command-line-interface">Command-Line Interface</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.html#command-line-options">Command-line options</a></li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#test-discovery">Test Discovery</a></li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#organizing-test-code">Organizing test code</a></li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#re-using-old-test-code">Re-using old test code</a></li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#skipping-tests-and-expected-failures">Skipping tests and expected failures</a></li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#distinguishing-test-iterations-using-subtests">Distinguishing test iterations using subtests</a></li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#classes-and-functions">Classes and functions</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.html#test-cases">Test cases</a><ul> <li class="toctree-l4"><a class="reference internal" href="unittest.html#deprecated-aliases">Deprecated aliases</a></li> </ul> </li> <li class="toctree-l3"><a class="reference internal" href="unittest.html#grouping-tests">Grouping tests</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.html#loading-and-running-tests">Loading and running tests</a><ul> <li class="toctree-l4"><a class="reference internal" href="unittest.html#load-tests-protocol">load_tests Protocol</a></li> </ul> </li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#class-and-module-fixtures">Class and Module Fixtures</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.html#setupclass-and-teardownclass">setUpClass and tearDownClass</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.html#setupmodule-and-teardownmodule">setUpModule and tearDownModule</a></li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="unittest.html#signal-handling">Signal Handling</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="unittest.mock.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">unittest.mock</span></code> — mock object library</a><ul> <li class="toctree-l2"><a class="reference internal" href="unittest.mock.html#quick-guide">Quick Guide</a></li> <li class="toctree-l2"><a class="reference internal" href="unittest.mock.html#the-mock-class">The Mock Class</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#calling">Calling</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#deleting-attributes">Deleting Attributes</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#mock-names-and-the-name-attribute">Mock names and the name attribute</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#attaching-mocks-as-attributes">Attaching Mocks as Attributes</a></li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="unittest.mock.html#the-patchers">The patchers</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#patch">patch</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#patch-object">patch.object</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#patch-dict">patch.dict</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#patch-multiple">patch.multiple</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#patch-methods-start-and-stop">patch methods: start and stop</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#patch-builtins">patch builtins</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#test-prefix">TEST_PREFIX</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#nesting-patch-decorators">Nesting Patch Decorators</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#where-to-patch">Where to patch</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#patching-descriptors-and-proxy-objects">Patching Descriptors and Proxy Objects</a></li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="unittest.mock.html#magicmock-and-magic-method-support">MagicMock and magic method support</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#mocking-magic-methods">Mocking Magic Methods</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#magic-mock">Magic Mock</a></li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="unittest.mock.html#helpers">Helpers</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#sentinel">sentinel</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#default">DEFAULT</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#call">call</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#create-autospec">create_autospec</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#any">ANY</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#filter-dir">FILTER_DIR</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#mock-open">mock_open</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#autospeccing">Autospeccing</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock.html#sealing-mocks">Sealing mocks</a></li> </ul> </li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="unittest.mock-examples.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">unittest.mock</span></code> — getting started</a><ul> <li class="toctree-l2"><a class="reference internal" href="unittest.mock-examples.html#using-mock">Using Mock</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mock-patching-methods">Mock Patching Methods</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mock-for-method-calls-on-an-object">Mock for Method Calls on an Object</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mocking-classes">Mocking Classes</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#naming-your-mocks">Naming your mocks</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#tracking-all-calls">Tracking all Calls</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#setting-return-values-and-attributes">Setting Return Values and Attributes</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#raising-exceptions-with-mocks">Raising exceptions with mocks</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#side-effect-functions-and-iterables">Side effect functions and iterables</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#creating-a-mock-from-an-existing-object">Creating a Mock from an Existing Object</a></li> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="unittest.mock-examples.html#patch-decorators">Patch Decorators</a></li> <li class="toctree-l2"><a class="reference internal" href="unittest.mock-examples.html#further-examples">Further Examples</a><ul> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mocking-chained-calls">Mocking chained calls</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#partial-mocking">Partial mocking</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mocking-a-generator-method">Mocking a Generator Method</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#applying-the-same-patch-to-every-test-method">Applying the same patch to every test method</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mocking-unbound-methods">Mocking Unbound Methods</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#checking-multiple-calls-with-mock">Checking multiple calls with mock</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#coping-with-mutable-arguments">Coping with mutable arguments</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#nesting-patches">Nesting Patches</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mocking-a-dictionary-with-magicmock">Mocking a dictionary with MagicMock</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mock-subclasses-and-their-attributes">Mock subclasses and their attributes</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#mocking-imports-with-patch-dict">Mocking imports with patch.dict</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#tracking-order-of-calls-and-less-verbose-call-assertions">Tracking order of calls and less verbose call assertions</a></li> <li class="toctree-l3"><a class="reference internal" href="unittest.mock-examples.html#more-complex-argument-matching">More complex argument matching</a></li> </ul> </li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="2to3.html">2to3 - Automated Python 2 to 3 code translation</a><ul> <li class="toctree-l2"><a class="reference internal" href="2to3.html#using-2to3">Using 2to3</a></li> <li class="toctree-l2"><a class="reference internal" href="2to3.html#fixers">Fixers</a></li> <li class="toctree-l2"><a class="reference internal" href="2to3.html#module-lib2to3"><code class="xref py py-mod docutils literal notranslate"><span class="pre">lib2to3</span></code> - 2to3’s library</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="test.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">test</span></code> — Regression tests package for Python</a><ul> <li class="toctree-l2"><a class="reference internal" href="test.html#writing-unit-tests-for-the-test-package">Writing Unit Tests for the <code class="xref py py-mod docutils literal notranslate"><span class="pre">test</span></code> package</a></li> <li class="toctree-l2"><a class="reference internal" href="test.html#running-tests-using-the-command-line-interface">Running tests using the command-line interface</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="test.html#module-test.support"><code class="xref py py-mod docutils literal notranslate"><span class="pre">test.support</span></code> — Utilities for the Python test suite</a></li> <li class="toctree-l1"><a class="reference internal" href="test.html#module-test.support.script_helper"><code class="xref py py-mod docutils literal notranslate"><span class="pre">test.support.script_helper</span></code> — Utilities for the Python execution tests</a></li> </ul> </div> <p>See also the Python development mode: the <a class="reference internal" href="../using/cmdline.html#id5"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> <code class="docutils literal notranslate"><span class="pre">dev</span></code> option and <span class="target" id="index-0"></span><a class="reference internal" href="../using/cmdline.html#envvar-PYTHONDEVMODE"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONDEVMODE</span></code></a> environment variable.</p> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h4>Previous topic</h4> <p class="topless"><a href="othergui.html" title="previous chapter">Other Graphical User Interface Packages</a></p> <h4>Next topic</h4> <p class="topless"><a href="typing.html" title="next chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">typing</span></code> — Support for type hints</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/3.7/Doc/library/development.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" 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