Test & Code - Python Testing & Development

Nicole is a software engineer and writer, and recently wrote about the trade-offs we make when deciding which tests to write and how much testing is enough.We talk about:Balancing schedule vs testingHow much testing is the right about of testingShould code coverage be measured and trackedGood refactoring can reduce code coverageIs it worth testing error conditions?Are rare error codes ok to just monitor?API drift and autospecMitigating riskDeciding what to test and what not to testFocus testing on key money-making features If there's a bug in this part of the code, how much business impact is there?Performance testing needs to approximately match real world workloadsCost of a service breaking vs the cost of creating, maintaining, and running testsKeeping test suites quick to minimize getting distractedLinks:Too much of a good thing: the trade-off we make with tests Load testing is hard, and the tools are... not great. But why?Yet Another Rust Resource (YARR!)Goodhart's law - "When a measure becomes a target,

If you've ever thought about starting a podcast or a SaaS project, you'll want to listen to this episode. Justin is one of the people who motivated me to get started podcasting. He's also running a successful SaaS company, transistor.fm, which hosts this podcast.Topics:PodcastingBuilding new SaaS (software as a service) productsBalancing work, side hustle, and familyGreat places to snowboard in British ColumbiaBTW. Links from the show:Transistor.fm - excellent podcast hosting, Justin is a co-founderHow to start a podcast in 2024Podcasts from JustinBuild your SaaS - currentBuild & Launch - an older one, but greatMegaMaker - from 2021 / 2022

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 virtualenvAstral 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:ruffAstraluv

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.

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

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-repeatpytest-rerunfailurespytest-flakefinderpytest-instafailWe talk about each of these in this episode.

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 TDDTest Driven Development by Example

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 dependenceTesting for dependencies using pluginsDebugging test dependenciesPlugins discussed:pytest-randomlypytest-reversepytest-random-order

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.

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 stdoutAdding debug and preview flags for debugging and testingAnd reverting to subprocess.run if you can't modify the code under testAlso, there's a full writeup and code samples available:Blog post: Testing argparse Applications Code Repo

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.

New course: "The Complete pytest Course"pytest-repeat, which I'm starting to contribute toGive `--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-repeatpytest-check is completely unrelated, but mentioned in the show

TDD (Test Driven Development) started from Test First Programming, and has been around at least since the 90's. However, software tools and available CI systems have changed quite a bit since then. Maybe it's time to re-examine the assumptions, practices, processes, and principles of TDD.  At least in the context of my software engineering career, modifications to TDD, at least the version of TDD as it's frequently taught, have been necessary. This is the start of a series focused on examining TDD and related lightweight practices and processes.Links from the show:From XPTest FirstUnit TestsAcceptance TestsTest-Driven Development (wikipedia)

On a recent episode of PythonBytes, I suggested it's hard to come up with good examples for pytest autouse fixtures, as there aren't very many good reasons to use them.  James Falcon was kind enough to reach out and correct me. In this episode, we describe:what fixtures arewhat autouse fixtures aregreat reasons to use them

Learn how to write nonfiction fast and well.Johanna Rothman joins the show to discuss writing nonfiction.Johanna's book: Free Your Inner Nonfiction Writer

Open Source is important to Intel and has been for a very long time.Joe Curley, vice president and general manager of software products and ecosystem, and Arun Gupta, vice president and general manager for open ecosystems, join the show to discuss open source, OneAPI, and open ecosystems at Intel.

Hynek joins the show to discuss towncrier. At the top of the towncrier documentation, it says "towncrier is a utility to produce useful, summarized news files (also known as changelogs) for your project."Towncrier is used by "Twisted, pytest, pip, BuildBot, and attrs, among others."This is the last of 3 episodes focused on keeping a CHANGELOG. Episode 200 kicked off the series with keepachangelog.com and Olivier Lacan In 201 we had Ned Batchelder discussing scriv.Special Guest: Hynek Schlawack.Links:Towncrier docsHow to Keep a Changelog in Markdown - Towncrier docsKeep a Changelogstructlog/CHANGELOG.md — Example of manually edited changelog.hatch-fancy-pypi-readmeMyST Markdown hatchling

Last week we talked about the importance of keeping a changelog. This week we talk with Ned Batchelder about scriv, a tool to help maintain that changelog.Scriv "is a command-line tool for helping developers maintain useful changelogs. It manages a directory of changelog fragments. It aggregates them into entries in a CHANGELOG file."Links:nedbat/scriv: Changelog management tool

A changelog is a file which contains a curated, chronologically ordered list of notable changes for each version of a project. This episode is about what a changelog is, with an interview with Olivier Lacan, creator of keepachangelog.com. The next two episodes talk about some tools to help software project teams keep changelogs while avoiding merge conflicts. Special Guest: Olivier Lacan.Links:Shields.ioKeep a Changelog"The Changelog" Podcast interview with Olivier LacanAn Open Source Rage Diamond

For a web side project to go from "working on desktop" to "live in the cloud", one decision that needs to be made is where to host everything. One option is Microsoft Azure. Lots of corporate sites use it. Is it right for side projects? Pamela Fox, a Cloud Advocate for Python at Microsoft, joins the show to help us with that question.Links:Python Bytes Episode #323pamelafox gitHub projectsDeploy a Python (Django or Flask) web app to AzureHosting Python Web Apps on Azure: A Price-OffDeploying a containerized FastAPI app to Azure Container AppsGetting started with hosting Python apps on AzurePricing Calculator for AzureApp Service Pricing pamelafox/flask-db-quiz-exampleTutorial: Deploy a Python Django or Flask web app with PostgreSQLPamela Fox on Mastodon