The Real Python Podcast

Eric Matthes: Maybe Don't Start With Unit Tests

Mar 7, 2025

Eric Matthes, author of "Python Crash Course," dives into the nuances of software testing. He argues against always starting with unit tests, suggesting that project type and audience should dictate testing strategies. Eric highlights the benefits of integration and end-to-end tests and shares insights on using PyTest, including fixtures and effective debugging with Python's assert statement. He emphasizes the importance of thoughtful test implementation and community engagement in refining testing practices.

01:10:48

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Eric Matthes

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Quick takeaways

Starting with integration or end-to-end tests can provide a better understanding of a project's overall functionality before implementing unit tests.

Utilizing PyTest allows developers to create versatile test suites that adapt and grow with their projects, which fosters code quality.

Fixtures in PyTest streamline the setup process for tests, ensuring consistent environments that enhance the reliability of functional evaluations.

Deep dives

Importance of Testing Strategy

Determining the right testing approach is crucial for any coding project. It's advised not to always start with unit tests, as this can lead to an overly rigid testing framework that may break with necessary code changes. Instead, the type of project and its audience should inform whether to begin with integration or end-to-end testing, which can better capture the intended functionality of a program. By focusing first on broader tests, developers can ensure that the overall behavior meets user needs before delving into granular unit tests.

Intro

3min

Navigating PyCon Proposals and Testing Techniques

6min

Navigating the Landscape of Software Testing

19min

Effective Debugging with Python's Assert Statement and PyTest

2min

Embracing PyTest for Effective Testing

10min

Navigating Testing: From Unit to Integration

17min

Exploring PyTest: Beyond Unit Testing

10min

Exploring Python and Music Synthesis

4min

Should you always start testing your code with unit tests? When does it make sense to look at integration or end-to-end testing as a first step instead? This week on the show, we speak with previous guest Eric Matthes about where to begin testing your code.

Eric is the author of the popular book Python Crash Course. Early in the development of the book, he decided to introduce testing and added a chapter on testing code with pytest.

Over the past couple of years, Eric has continued to consider when and where to test a project’s code. He thinks there are hazards to always starting with unit tests. The type of project and its audience should determine what kind of testing to employ initially.

We discuss using pytest to develop integration tests on multiple types of projects. We also explore fixtures and what goes into building a test suite. Eric also shares criteria for when and where it makes sense to add unit tests to a project.

Course Spotlight: Using Python’s assert to Debug and Test Your Code

In this course, you’ll learn how to use Python’s assert statement to document, debug, and test code in development. You’ll learn how assertions might be disabled in production code, so you shouldn’t use them to validate data. You’ll also learn about a few common pitfalls of assertions in Python.

Topics:

00:00:00 – Introduction
00:01:47 – Submitting talks to conferences
00:04:10 – Don’t start with unit tests!
00:07:35 – How did you start with testing?
00:11:30 – Example of a project needing tests
00:14:54 – Defining types of tests
00:16:44 – Integration vs end-to-end tests
00:19:09 – When should you build tests?
00:22:13 – Trade offs of integration vs unit tests
00:24:05 – Why is there push back on this idea?
00:27:36 – Video Course Spotlight
00:29:09 – Using pytest
00:33:24 – Transcripts project example
00:37:03 – py-image-border project
00:40:29 – Criteria for when you should write unit tests
00:48:51 – How to practice writing tests
00:50:28 – Building an integration test and pytest fixtures
00:55:05 – What’s in the test folder?
00:56:31 – Idea for a PyCon tutorial on implementing tests
00:57:29 – Other pytest advice and parametrization
01:01:13 – Caveats to not starting with unit tests
01:02:30 – pytest documentation and other advice
01:05:23 – How to reach Eric online
01:06:47 – What are you excited about in the world of Python?
01:08:23 – What do you want to learn next?
01:09:48 – What conferences are you attending?
01:10:06 – Thanks and goodbye

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The Real Python Podcast

Eric Matthes: Maybe Don't Start With Unit Tests

Episode guests

Podcast summary created with Snipd AI

Quick takeaways

Deep dives

Importance of Testing Strategy

Utilizing PyTest for Integration Tests

Managing Test Suites with PyTest

The Role of Fixtures in Testing

Real-World Testing Examples

Remember Everything You Learn from Podcasts