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<!DOCTYPE html>

<head>

<title>Unit Testing - Full Stack Python</title>

<!--[if lt IE 9]>

<![endif]-->

</head>

<body>

<h2 style="color: #fff; margin: 20px 40px 0 0;"><a href="https://www.gumroad.com/l/python-deployments" style="color: #fff">The Full Stack Python Guide to Deployments book</a> has been released!</h2>

</div>

</div> <a href="https://github.com/makaimc/fullstackpython.com"><img style="position: absolute; top: 0; right: 0; border: 0;" src="/theme/img/fork.png" alt="Fork me on GitHub"></a>

<span class="logo-title"><a href="/">Full Stack Python</a></span>

</div>

</div><div class="row">

<h1>Unit testing</h1>

<p>Unit testing is a method of determining the correctness of a single function

isolated from a larger codebase. The idea is that if all the atomic units

of an application work as intended in isolation, then integrating them

together as intended is much easier.</p>

<h2>Why is unit testing important?</h2>

<p>Unit testing is just one form of <a href="/testing.html">testing</a> that works in

combination with other testing approaches to wring out the bugs from a

piece of software being developed. When several functions and classes are

put together it's often difficult to determine the source of a problem if

several bugs are occurring at the same time. Unit testing helps eliminate

as many of the individual bugs as possible so when the application comes

together as a whole the separate parts work as correct as possible. Then

when issues arise they can often be tracked down as unintended consequences

of the disparate pieces not fitting together properly.</p>

<h2>Unit testing tools</h2>

<p>There are many tools for creating tests in Python. Some of these tools, such

as pytest, replace the built-in unittest framework. Other tools, such as

nose, are extensions that ease test case creation. Note that many of these

tools are also used for <a href="/integration-testing.html">integration testing</a>

by writing the test cases to exercise multiple parts of code at once.</p>

<ul>

<li>

<p><a href="https://docs.python.org/3/library/unittest.html">unittest</a>

is the built-in standard library tool for testing Python code.</p>

</li>

<li>

<p><a href="http://pytest.org/latest/">pytest</a> is a complete testing tool that

emphasizes backwards-compatibility and minimizing boilerplate code.</p>

</li>

<li>

<p><a href="https://nose.readthedocs.org/en/latest/">nose</a> is an extension to

unittest that makes it easier to create and execute test cases.</p>

</li>

<li>

<p><a href="https://github.com/Yelp/Testify/">testify</a> was a testing framework

meant to replace the common unittest+nose combination. However, the team

behind testify is transitioning to pytest so it's recommended you do

not use testify for new projects.</p>

</li>

</ul>

<h3>Unit testing resources</h3>

<ul>

<li>

<p><a href="https://realpython.com/blog/python/the-minimum-viable-test-suite/">The Minimum Viable Test Suite</a>

shows how to set unit tests and integration tests for a Flask example

application.</p>

</li>

<li>

<p><a href="http://www.diveintopython3.net/unit-testing.html">Dive into Python 3's chapter on unit testing</a>

has a complete example with code and a detailed explanation for creating

unit testing with the

<a href="https://docs.python.org/3/library/unittest.html">unittest</a> module.</p>

</li>

<li>

<p><a href="https://jeffknupp.com/blog/2013/12/09/improve-your-python-understanding-unit-testing/">Understanding unit testing</a>

explains why testing is important and shows how to do it effectively in

your applications.</p>

</li>

<li>

<p><a href="http://www.drdobbs.com/testing/unit-testing-with-python/240165163">Unit testing with Python</a>

provides a high-level overview of testing and has diagrams to demonstrate

what's going on in the testing cycle.</p>

</li>

<li>

<p>The Python wiki has a page with a list of

<a href="https://wiki.python.org/moin/PythonTestingToolsTaxonomy">Python testing tools and extensions</a>.</p>

</li>

<li>

<p><a href="http://blog.fogcreek.com/working-effectively-with-unit-tests-interview-with-jay-fields/">Working Effectively with Unit Tests</a>

is an interview with the author of a book by the title where he shares

some of the insight he's learned on the topic.</p>

</li>

<li>

<p><a href="http://blog.kevinastone.com/generate-your-tests.html">Generate your tests</a>

shows how to write a test generator that works with the <code>unittest</code>

framework.</p>

</li>

</ul>

<h3>What else do you want to learn about testing?</h3>

<p class="under-btn">What code metrics should I be aware of?</p> </div>

</div>

<p class="under-btn">How do I go about testing my Python code?</p> </div>

</div>

<p class="under-btn">Can I automate testing and deployments for my app?</p> </div>

</div>

</div><div id="mc_embed_signup">

<h4>Sign up here to receive an email with major updates to this site and Python tutorials delivered to your inbox once a month.</h4>

</div>

</div>

</form>

</div>

<p style="font-size: .8em; margin-top: 10px;">Searching for a complete, step-by-step deployment walkthrough? Learn more about <a href="http://www.deploypython.com/">The Full Stack Python Guide to Deployments book</a>.

</p>

</div>

</div> <div class="panel panel-success">

<h3 class="panel-head"><a href="/table-of-contents.html" style="color: #fff;">Table of Contents</a></h3>

</div>

<a href="/introduction.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Introduction</a>

<a href="/learning-programming.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Learning Programming</a>

<a href="/why-use-python.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Why Use Python?</a>

<a href="/python-2-or-3.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Python 2 or 3?</a>

<a href="/enterprise-python.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Enterprise Python</a>

<a href="/best-python-resources.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Best Python Resources</a>

<a href="/best-python-videos.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Best Python Videos</a>

<a href="/development-environments.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Development Environments</a>

<a href="/emacs.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Emacs</a>

<a href="/generators.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Generators</a>

<a href="/comprehensions.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Comprehensions</a>

<a href="/web-frameworks.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Web Frameworks</a>

<a href="/django.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Django</a>

<a href="/flask.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Flask</a>

<a href="/bottle.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Bottle</a>

<a href="/pyramid.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Pyramid</a>

<a href="/morepath.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Morepath</a>

<a href="/other-web-frameworks.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Other Web Frameworks</a>

<a href="/web-design.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Web Design</a>

<a href="/cascading-style-sheets.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Cascading Style Sheets</a>

<a href="/javascript.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>JavaScript</a>

<a href="/websockets.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>WebSockets</a>

<a href="/web-application-security.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Web Application Security</a>

<a href="/static-site-generator.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Static Site Generators</a>

<a href="/databases.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Databases</a>

<a href="/no-sql-datastore.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>NoSQL Data Stores</a>

<a href="/object-relational-mappers-orms.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Object-relational Mappers (ORMs)</a>

<a href="/application-programming-interfaces.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Application Programming Interfaces</a>

<a href="/api-integration.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>API Integration</a>

<a href="/api-creation.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>API Creation</a>

<a href="/deployment.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Deployment</a>

<a href="/servers.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Servers</a>

<a href="/platform-as-a-service.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Platform-as-a-service</a>

<a href="/operating-systems.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Operating Systems</a>

<a href="/web-servers.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Web Servers</a>

<a href="/wsgi-servers.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>WSGI Servers</a>

<a href="/source-control.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Source Control</a>

<a href="/application-dependencies.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Application Dependencies</a>

<a href="/static-content.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Static Content</a>

<a href="/task-queues.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Task Queues</a>

<a href="/configuration-management.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Configuration Management</a>

<a href="/continuous-integration.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Continuous Integration</a>

<a href="/logging.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Logging</a>

<a href="/monitoring.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Monitoring</a>

<a href="/web-analytics.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Web Analytics</a>

<a href="/docker.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Docker</a>

<a href="/caching.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Caching</a>

<a href="/microservices.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Microservices</a>

<a href="/testing.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Testing</a>

<a href="/unit-testing.html" class="list-group-item smaller-item active" style='font-family: "Helvetica Neue",sans-serif;'>Unit Testing</a>

<a href="/integration-testing.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Integration Testing</a>

<a href="/code-metrics.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Code Metrics</a>

<a href="/debugging.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Debugging</a>

<a href="/what-full-stack-means.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>What "Full Stack" Means</a>

<a href="/change-log.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Change Log</a>

<a href="/future-directions.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>Future Directions</a>

<a href="/about-author.html" class="list-group-item smaller-item " style='font-family: "Helvetica Neue",sans-serif;'>About the Author</a>

</div>

</p>

</div>

</div> <div class="panel panel-success">

<div class="panel-heading"><h3 class="panel-head">Unit Testing</h3></div>

Major updates are tweeted via

<a href="https://twitter.com/fullstackpython">@fullstackpython</a>.

<hr/>

Need more detailed tutorials than you see here?

<a href="http://www.deploypython.com/">Learn more about The Full Stack Python Guide to Deployments book.</a>

</div>

</div></div>

<hr/>

</div>

<a href="http://www.mattmakai.com/" class="underline">Matt Makai</a>

2015

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fullstackpython.com/unit-testing.html at patch-1 · nullism/fullstackpython.com · GitHub

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