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						</div><p>When you&#8217;re building something in Python—whether it&#8217;s a personal project, an API, or a startup idea—one thing is certain: bugs happen. And while debugging can be fun (sometimes), wouldn’t it be better to catch issues before they cause problems?</p>
<p>That’s where testing comes in. In today’s blog, we’ll explore how to test and run your Python applications using Pytest, one of the most popular and beginner-friendly testing tools out there. We’ll also walk through some examples to show you exactly how to write and execute tests using Pytest.</p>
<p>Let’s dive in!</p>
<h2>How to Test Applications in Python?</h2>
<p>Testing is all about making sure your code does what it’s supposed to. In Python, testing generally falls into a few categories:</p>
<ul>
<li>
<p><strong>Unit Testing</strong>: Testing individual functions or methods.</p>
</li>
<li>
<p><strong>Integration Testing</strong>: Making sure different parts of your app work well together (e.g., API + DB).</p>
</li>
<li>
<p><strong>Functional Testing(E2E)</strong>: Testing end-to-end flows, like a user login.</p>
</li>
</ul>
<p>Wait, you can also test your Python application manually, but it will take a lot of your time. And what if your application has more files and functions? You can&#8217;t test it manually, so that’s why every language has frameworks or libraries to automate the process. One such framework is Pytest for Python.</p>
<p>While Python also has a built-in unittest module, most developers prefer Pytest for its simplicity and power.</p>
<p>Enough theory you now know why we are testing and why we prefer Pytest over Unittest, so let’s see some code.</p>
<h2>What is Pytest??</h2>
<p>Pytest is a testing framework for Python that makes it easy to write small, scalable tests. It offers a new approach to unit testing, which is less complicated and more fun</p>
<h2>How to Install Pytest</h2>
<p><strong>Super simple. Just run:</strong></p>
<pre><code>python
pip install -U pytest</code></pre>
<p>Note: Make sure you&#8217;re in a virtual environment</p>
<p><strong>To verify it’s installed:</strong></p>
<pre><code>python
pytest --version</code></pre>
<p><strong>Here is how the Output will look like:</strong></p>
<p><img decoding="async" src="https://wp.keploy.io/wp-content/uploads/2025/05/Here-is-how-the-Output-will-look-like-scaled.webp" alt="How to install pytest" /></p>
<h2>Writing Our First Pytest Test</h2>
<p>Let’s write a basic function and test it using Pytest.</p>
<p><strong>Step 1: Create an file named calculator.py</strong></p>
<pre><code class="language-python">def add(a, b):
    return a + b</code></pre>
<p><strong>Step 2: Create a test file named test_calculator.py</strong></p>
<pre><code>python
from calculator import add

def test_add():
    assert add(2, 3) == 5</code></pre>
<p><strong>Step 3: How to Run the pytest? Use the below command</strong></p>
<pre><code>python
pytest</code></pre>
<p>Pytest will discover any files starting with test_ and run them automatically. No need for classes or boilerplate code.</p>
<p><strong>Output of our first example</strong></p>
<p><img decoding="async" src="https://wp.keploy.io/wp-content/uploads/2025/05/Output-of-our-first-example-scaled.webp" alt="" /></p>
<p><strong>Let’s make some changes in the test_calculator.py:</strong></p>
<pre><code>python
from calculator import add

def test_add():
    assert add(2, 3) == 6</code></pre>
<p>Even 5-year-old kids know 2 + 3 = 5, but let’s test this with Pytest and see what output we’re getting:</p>
<p><strong>Output</strong>:</p>
<p><img decoding="async" src="https://wp.keploy.io/wp-content/uploads/2025/05/56aa408c-bfca-4253-b1b6-7cc556ab-scaled.webp" alt="" /></p>
<p>Guess what? Our test failed because in the logic we are adding two numbers, but in the test we’re asserting 2 + 3 = 6 , so it failed.</p>
<h2>Let’s see an another simple pytest Example:</h2>
<p>Example 2: Testing a String Function</p>
<p><strong>Let’s test if a string is a palindrome.</strong></p>
<pre><code>python
def is_palindrome(word):
    return word == word[::-1]</code></pre>
<p>Let’s write pytest for the above function</p>
<pre><code>python
def test_is_palindrome():
    assert is_palindrome(&quot;madam&quot;) is True
    assert is_palindrome(&quot;banana&quot;) is True</code></pre>
<p>Let’s see the Output:</p>
<p><strong>By the way if you want to run the specific Test file you can use:</strong></p>
<pre><code>python
pytest &lt;file_name.py&gt;</code></pre>
<p><img decoding="async" src="https://wp.keploy.io/wp-content/uploads/2025/05/How-to-run-specific-pytest-file-scaled.webp" alt="How to run specific pytest file" /></p>
<p>You can see from the output, banana is not the palindrome so the test failed.</p>
<h2><strong>Advantages of Pytest</strong></h2>
<ul>
<li>
<p>Simple and readable syntax.</p>
</li>
<li>
<p>No boilerplate—just write tests as functions.</p>
</li>
<li>
<p>Rich ecosystem (plugins, fixtures, parametrize).</p>
</li>
<li>
<p>Great for both small and large projects.</p>
</li>
<li>
<p>Easy to integrate with CI tools.</p>
</li>
</ul>
<h2><strong>Tired of Writing Code for Tests? Let’s See How</strong> <a href="https://keploy.io/"><strong>Keploy</strong></a> <strong>Helps You</strong></h2>
<p>Wait, even though we have a lot of advantages with Pytest, there’s still one big problem: we have to manually write tests for the application. And let’s be real we’re busy shipping features.</p>
<p>Don’t get misled by the above example. Those were just very simple programs I wrote to help beginners understand how Pytest works. But in reality, it’s tough to write a test case for each and every function.</p>
<p>That’s exactly where Keploy comes in.</p>
<p><a href="https://keploy.io/">Keploy</a> is a <strong>zero-code testing platform</strong> it automatically writes unit test cases for you by analyzing your source code. And no, I know what you’re thinking—it’s not just another ChatGPT wrapper! Keploy’s unit testing is completely different from other providers.</p>
<p>You can use Keploy’s unit testing product via the <strong>VSCode extension</strong>, or try the <strong>Keploy PR Agent</strong>, which automatically writes unit test cases whenever someone raises a PR.</p>
<p>Just remember, we’re in 2025, not 2018 or 2019. So, let’s start testing like it’s 2025.</p>
<p><strong>What are you waiting for? Just give it a try!</strong></p>
<p>Links to VScode Extension: <a href="https://marketplace.visualstudio.com/items?itemName=Keploy.keployio">https://marketplace.visualstudio.com/items?itemName=Keploy.keployio</a></p>
<p>Links to Github PR agent: <a href="https://github.com/apps/keploy">https://github.com/apps/keploy</a></p>
<h2>Conclusion</h2>
<p>Testing doesn’t have to be hard. With Pytest, you get a simple, readable, and powerful framework that grows with your project.</p>
<p>In today’s blog, we’ve seen how to run a Pytest program. Wait those were just very basic programs! There are many more things to explore. Pytest has a variety of assert statements readily available in the docs you should definitely try those out too.</p>
<p>So, go ahead write your first pytest today and understand how to run it. You’ll thank yourself later when you catch a bug before it hits production.</p>
<p>If you want to learn more about the Python testing with pytest, I highly recommend checking out this <a href="https://keploy.io/blog/community/python-testing-with-pytest-features-best-practices?trk=article-ssr-frontend-pulse_little-text-block">blog</a></p>
<p>Don’t forget to try <a href="https://keploy.io/">Keploy</a> and if you found Keploy useful, give it a star. Not in the sky 🌟—but on the repo! <a href="https://github.com/keploy/keploy">https://github.com/keploy/keploy</a></p>
<h2>FAQ’s</h2>
<ol>
<li>
<h3>Is Pytest only for unit testing?</h3>
<p>Nope! Pytest can also be used for integration and functional testing. Just use fixtures and mocks to set up your dependencies.</p>
</li>
<li>
<h3>Do I need to write tests manually with Keploy?</h3>
<p>Nope! With Keploy Unit testing agent even you dont need to write a prompt also. Just install it in your VScode or Github and let see keploy in action.</p>
</li>
<li>
<h3>Can I use Pytest in a CI pipeline?</h3>
<p>Yes! Pytest works great with GitHub Actions, GitLab CI, Jenkins, and more. Just add a step like pytest in your pipeline.</p>
</li>
<li>
<h3>Pytest vs Unittest — Which one is better?</h3>
<p>To be honest, Both have their pros, but most developers prefer Pytest for its cleaner syntax, less boilerplate, and powerful features like fixtures and plugins.<br />
If you’re starting fresh, go with Pytest. But if you&#8217;re maintaining legacy code that already uses unittest, it&#8217;s still a solid choice.</p>
</li>
<li>
<h3>Can I use Pytest with Django or Flask apps?</h3>
<p>Absolutely! Pytest works great with both Django and Flask. In fact, many devs prefer it over the built-in Django test runner because of its flexibility and powerful fixture system. There are even plugins like pytest-django and pytest-flask that make integration seamless.</p>
</li>
</ol>

         
        
                    

                    
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