121: Industrial 3D Printing & Python, Finite State Machines, and Simulating Hardware - Len Wanger

Charlie Marsh and team are using Rust to make Python tooling faster.

• Ruff can take the place of Flake8, isort, and Black, and so much more.
• uv can take the place of pip, pip-tools, and virtualenv
• Astral is Charlie's venture backed company, and what they have with `ruff` and `uv` is just the start.

Since uv is the newest tool, there's quite a bit of the discussion diving into uv.

Links:

• ruff
• Astral
• uv

Sponsored by PyCharm Pro

• Use code PYTEST for 20% off PyCharm Professional at jetbrains.com/pycharm
• First 10 to sign up this month get a free month of AI Assistant
• See how easy it is to run pytest from PyCharm at pythontest.com/pycharm

The Complete pytest Course

• For the fastest way to learn pytest, go to courses.pythontest.com
• Whether your new to testing or pytest, or just want to maximize your efficiency and effectiveness when testing.

Software engineers that move into leadership roles have a struggle between learning leadership skills, maintaining technical skills, and learning new leadership and technical skills. 
Matt Makai went from individual contributor to developer relations to leadership in devrel. 
We discuss how to stay technical, as well as dive into some results of his studies in how companies use developer relationship channels.

Sponsored by PyCharm Pro

• Use code PYTEST for 20% off PyCharm Professional at jetbrains.com/pycharm
• First 10 to sign up this month get a free month of AI Assistant
• See how easy it is to run pytest from PyCharm at pythontest.com/pycharm

The Complete pytest Course

• For the fastest way to learn pytest, go to courses.pythontest.com
• Whether your new to testing or pytest, or just want to maximize your efficiency and effectiveness when testing.

If you haven't tried running automated tests, especially with pytest,  in VS Code recently, you should take another look.
The Python for VS Code interface for testing, especially for pytest, has changed recently. 
On this episode we discuss the change with the software engineer working on the pytest changes, Eleanor Boyd, and the product manager, Courtney Webster. 

Links from the episode:

• Blog post announcing the rewrite  
• Code repo for questions, comments, issues etc

The Complete pytest Course

• Level up your testing skills and save time during coding and maintenance.
• Check out courses.pythontest.com

If a test fails in a test suite, I'm going to want to re-run the test. I may even want to re-run a test, or a subset of the suite, a bunch of times.  
There are a few pytest plugins that help with this:

• pytest-repeat
• pytest-rerunfailures
• pytest-flakefinder
• pytest-instafail

We talk about each of these in this episode.

Sponsored by PyCharm Pro

• Use code PYTEST for 20% off PyCharm Professional at jetbrains.com/pycharm
• First 10 to sign up this month get a free month of AI Assistant
• See how easy it is to run pytest from PyCharm at pythontest.com/pycharm

The Complete pytest Course

• For the fastest way to learn pytest, go to courses.pythontest.com
• Whether your new to testing or pytest, or just want to maximize your efficiency and effectiveness when testing.

In 2002, Kent Beck released a book called  "Test Driven Development by Example".
In December of 2023, Kent wrote an article called "Canon TDD".
With Kent's permission, this episode contains the full content of the article.

Brian's commentary is saved for a followup episode.

Links:

• Canon TDD
• Test Driven Development by Example

The Complete pytest Course

• Level up your testing skills and save time during coding and maintenance.
• Check out courses.pythontest.com

We want to be able to run tests in a suite, and debug them in isolation, and have the behavior be the same.  
If the behavior is different in isolation vs in a suite, it's a nightmare to debug. 

In this episode, we'll talk about:

• Causes of dependence
• Testing for dependencies using plugins
• Debugging test dependencies

Plugins discussed:

• pytest-randomly
• pytest-reverse
• pytest-random-order

Sponsored by PyCharm Pro

• Use code PYTEST for 20% off PyCharm Professional at jetbrains.com/pycharm
• First 10 to sign up this month get a free month of AI Assistant
• See how easy it is to run pytest from PyCharm at pythontest.com/pycharm

The Complete pytest Course

• For the fastest way to learn pytest, go to courses.pythontest.com
• Whether your new to testing or pytest, or just want to maximize your efficiency and effectiveness when testing.

Test Driven Development. Red, Green, Refactor. 

• Do we have to do the refactor part? 
• Does the refactor at the end include tests? 
• Or can I refactor the tests at any time?
• Why is refactor at the end? 

This episode is to talk about this with a an example.

Sponsored by PyCharm Pro

• Use code PYTEST for 20% off PyCharm Professional at jetbrains.com/pycharm
• First 10 to sign up this month get a free month of AI Assistant
• See how easy it is to run pytest from PyCharm at pythontest.com/pycharm

The Complete pytest Course

• For the fastest way to learn pytest, go to courses.pythontest.com
• Whether your new to testing or pytest, or just want to maximize your efficiency and effectiveness when testing.

How do you test the argument parsing bit of an application that uses argparse?

This episode covers:

• Design for Test: Structuring your app or script so it's easier to test.
• pytest & capsys for testing stdout
• Adding debug and preview flags for debugging and testing
• And reverting to subprocess.run if you can't modify the code under test

Also, there's a full writeup and code samples available:

• Blog post: Testing argparse Applications 
• Code Repo

The Complete pytest Course

• Level up your testing skills and save time during coding and maintenance.
• Check out courses.pythontest.com

Why on earth would you want to write a test with no assert statements?
After all, aren't assert statements how you decide wether a test passes or fails?

In this episode, we walk through a handful of useful examples of test code without asserts.
We also talk about how these types of tests are a great way to dip your toe into testing.

Sponsored by PyCharm Pro

• Use code PYTEST for 20% off PyCharm Professional at jetbrains.com/pycharm
• First 10 to sign up this month get a free month of AI Assistant
• See how easy it is to run pytest from PyCharm at pythontest.com/pycharm

The Complete pytest Course

• For the fastest way to learn pytest, go to courses.pythontest.com
• Whether your new to testing or pytest, or just want to maximize your efficiency and effectiveness when testing.

• Podcast name: "Test & Code" -> "Python Test"
• Python Bytes Podcast
• Python People Podcast
• Python Test Podcast <- you are here
  • which is still, at least for now, at testandcode.com
• New course: "The Complete pytest Course"
• pytest-repeat, which I'm starting to contribute to
  • Give `--repeat-scope` a try. You can use it to change from repeating every test to repeating the session, module, or class.
• pytest-flakefinder, which is an alternative to pytest-repeat
• pytest-check is completely unrelated, but mentioned in the show