Your test suite tells you about the quality of your code under test. Mutation testing is a way to tell you about the quality of your test suite. Anders Hovmöller wrote mutmut (https://mutmut.readthedocs.io/) for mutation testing in Python, and can be used with pytest, unittest, and others. In this episode, Anders explains mutation testing, how mutation testing with mutmut works, and good workflows. Special Guest: Anders Hovmöller.

Test & Code: Python Software Testing & Engineering

138: Mutation Testing in Python with mutmut - Anders Hovmöller

Matt Harrison, author of many Python books, is putting together a course, Effective Book Authoring, to help other people write and publish books. As part of this course, he's including interviews with people who have already written books, including me. This is that interview. We discuss: * Why I wrote "Python Testing with pytest" * Self publishing vs working with a publisher * The writing, editing, and publishing process * Writing format * Book promotion * Advice to other writers Special Guest: Matt Harrison.

137: Become an Author - Matt Harrison interviews Brian Okken

Wearable technology is not just smart consumer devices like watches and activity trackers. Wearable tech also includes one off projects by designers, makers, and hackers and there are more and more people producing tutorials on how to get started. Wearable tech is also a great way to get both kids and adults excited about coding, electronics, and in general, engineering skills. Sophy Wong is a designer who makes really cool stuff using code, technology, costuming, soldering, and even jewelry techniques to get tech onto the human body. Sophy joins the show to answer my many questions about getting started safely with wearable tech. Some of the questions and topics: Can I wash my clothing if I've added tech to it? Is there any danger in wearing technology or building wearable tech? Are there actual wires and cables conductive thread in the fabric and textiles of some wearable tech projects? What's a good starter project? Especially if I want to do a wearable tech project with my kids? Dealing with stretch with clothing and non-bendy electronics. Some questions around the Sophy Wong and HackSpace "Wearable Tech Projects" book. How did you get into wearable tech? Do you have a favorite project? Can I get into wearable tech if I don't know how to code or solder? Are these projects accessible to people with limited budgets? Making projects so you can reuse the expensive bits on multiple projects. Special Guest: Sophy Wong.

136: Wearable Technology - Sophy Wong

All test suites start fast. But as you grow your set of tests, each test adds a little bit of time to the suite. What can you do about it to keep test suites fast? Some things, like parallelization, are applicable to many domains. What about, for instance, Django applications? Well, Adam Johnson has thought about it a lot, and is here to tell us how we can speed up our Django test suites. Topics include: parallelizing tests moving from disk to memory using fake data and factory functions targeted mocking Special Guest: Adam Johnson.

135: Speeding up Django Test Suites

Within software projects, there are lots of metrics we could measure. But which ones really matter. Instead of a list, Benjamin Harding shares with us a way of thinking about business outcomes that can help us with every day decision making. We talk about: * Business outcomes vs vanity metrics * As a developer, how do you keep business outcomes in mind * Thinking about customer value all the time * Communicating decisions and options in terms of costs and impact on business outcomes * Company culture and it's role in reinforcing a business outcome mindset * And even the role of team lead as impact multiplier I really enjoyed this conversation. But I admit that at first, I didn't realize how important this is on all software development. Metrics are front and center in a web app. But what about a service, or an embedded system with no telemetry. It still matters, maybe even more so. Little and big decisions developers face every day that have impact on costs and benefits with respect to customer value and business outcome, even if it's difficult to measure. Special Guest: Benjamin Harding.

134: Business Outcomes and Software Development

Hackathons have been spreading around the world; many at university campuses. Major League Hacking, MLH, has been encouraging and helping hackathons. Hacking can be thought of as tinkering. Taking things apart and putting them back together as an interesting experience. There's always been some of this as part of software culture. The people at Major League Hacking have taken this to a whole new level, bringing together Tech creators who enjoy playing around with and crating new technology, on campuses, and now in virtual spaces, all over the world. Jonathon Gottfried, one of the cofounders of Major League Hacking, joins the show to talk about: hacker meetups and events hackathons what it's like to go to a hackathon how to help out with hackathons as an experienced engineer, even virtually as a mentor hackathons continuing virtually during the pandemic internships and fellowships on open source projects to help students gain experience, even during the pandemic MLH approach to internships, giving interns a support group, including peers, mentors, and project maintainers and MLH itself Special Guest: Jon Gottfried.

133: Major League Hacking - Jon Gottfried

Using mock objects during testing in Python. Anna-Lena joins the podcast to teach us about mocks and using unittest.mock objects during testing. We discuss: - the different styles of using mocks - pros and cons of mocks - dependency injection - adapter pattern - mock hell - magical universe - and much more Special Guest: Anna-Lena Popkes.

132: mocking in Python - Anna-Lena Popkes

Some people avoid writing tests. Some drudge through it painfully. There is a better way. In this episode, I'm going to share some advice from Luke Plant on how to "Test Smarter, Not Harder" (https://lukeplant.me.uk/blog/posts/test-smarter-not-harder/).

131: Test Smarter, Not Harder

virtualenv supports six shells: bash, csh, fish, xonsh, cmd, posh. Each handles prompts slightly differently. Although the virtualenv custom prompt behavior should be the same across shells, Brian Skinn noticed inconsistencies. He set out to fix those inconsistencies. That was the start of an adventure in open source collaboration, shell prompt internals, difficult test problems, and continuous integration quirks. Brian Skinn initially noticed that on Windows cmd, a space was added between a prefix defined by --prompt and the rest of the prompt, whereas on bash no space was added. For reference, there were/are three nominal virtualenv prompt modification behaviors, all of which apply to the prompt changes that are made at the time of virtualenv activation: If the environment variable VIRTUAL_ENV_DISABLE_PROMPT is defined and non-empty at activation time, do not modify the prompt at all. Otherwise: If the --prompt argument was supplied at creation time, use that argument as the prefix to apply to the prompt; or, If the --prompt argument was not supplied at creation time, use the default prefix of "({{ envname }}) " as the prefix (the environment folder name surrounded by parentheses, and with a trailing space after the last paren. Special Guest: Brian Skinn.

130: virtualenv activation prompt consistency across shells - an open source dev and test adventure - Brian Skinn

I asked people on twitter to fill in "How do I test _____?" to find out what people want to know how to test. Lots of responses. David Lord agreed to answer them with me. In the process, we come up with lots of great general advice on how to test just about anything. Specific Questions people asked: What makes a good test? How do you test web app performance? How do you test cookie cutter templates? How do I test my test framework? How do I test permission management? How do I test SQLAlchemy models and pydantic schemas in a FastAPI app? How do I test warehouse ETL code? How do I test and mock GPIO pins on hardware for code running MicroPython on a device? How do I test PyQt apps? How do I test web scrapers? Is it the best practice to put static html in your test directory or just snippets stored in string variables? What's the best way to to test server client API contracts? How do I test a monitoring tool? We also talk about: What is the Flask testing philosophy? What do Flask tests look like? Flask and Pallets using pytest Code coverage Some of the resulting testing strategies: Set up some preconditions. Run the function. Get the result. Don't test external services. Do test external service failures. Don't test the frameworks you are using. Do test your use of a framework. Use open source projects to learn how something similar to your project tests things. Focus on your code. Focus on testing your new code. Try to architect your application such that actual GUI testing is minimal. Split up a large problem into smaller parts that are easier to test. Nail down as many parts as you can. Special Guest: David Lord.

129: How to Test Anything - David Lord

Software tests should be order independent. That means you should be able to run them in any order or run them in isolation and get the same result. However, system state often gets in the way and order dependence can creep into a test suite. One way to fight against order dependence is to randomize test order, and with pytest, we recommend the plugin pytest-randomly to do that for you. The developer that started pytest-randomly and continues to support it is Adam Johnson, who joins us today to discuss pytest-randomly and another plugin he also wrote, called pytest-reverse. Special Guest: Adam Johnson.

128: pytest-randomly - Adam Johnson

Many people have been working from home now that are not used to working from home. Or at least are working from home more than they ever did before. That's definitely true for me. Even though I've been working from home since March, I wanted some tips from people who have been doing it longer. Julian Sequeira, of PyBites fame, has been working from home for about a year. Reuven Lerner, an amazing Python trainer, has been working from home for much longer. We originally had a big list of WFH topics. But we had so much fun with the tips and tricks part, that that's pretty much the whole episode. But there's lots of great tips and tricks, so I'm glad we focused on that. Special Guests: Julian Sequeira and Reuven Lerner.

127: WFH, WTF? - Tips and Tricks for Working From Home - Reuven Lerner & Julian Sequeira

Researches and others using data science and software need to follow solid software engineering practices. This is a message that Joel Grus has been promoting for some time. Joel joins the show this week to talk about data science, software engineering, and even Fizz Buzz. Topics include: Software Engineering practices and data science Difficulties with Jupyter notebooks Code reviews on experiment code Unit tests on experiment code Finding bugs before doing experiments Tests for data pipelines Tests for deep learning models Showing researchers the value of tests by showing the bugs found that wouldn't have been found without them. "Data Science from Scratch" book Showing testing during teaching Data Science "Ten Essays on Fizz Buzz" book Meditations on Python, mathematics, science, engineerign and design Testing Fizz Buzz Different algorithms and solutions to an age old interview question. If not Fizz Buzz, what makes a decent coding interview question. pytest hypothesis Math requirements for data science Special Guest: Joel Grus.

126: Data Science and Software Engineering Practices ( and Fizz Buzz ) - Joel Grus

pytest 6 is out. Specifically, 6.0.1, as of July 31. And there's lots to be excited about. Anthony Sottile joins the show to discuss features, improvements, documentation updates and more. Full release notes / changelog (https://docs.pytest.org/en/stable/changelog.html) Some of what we talk about: How to update (at least, how I do it) Run your test suites with 5.4.3 or whatever the last version you were using Update to 6 Run again. Same output? Probably good. If there are any warnings, maybe fix those. You can also run with pytest -W error to turn warnings into errors. Then find out all the cool stuff you can do now New Features pytest now supports pyproject.toml files for configuration. but remember, toml syntax is different than ini files. mostly quotes are needed pytest now includes inline type annotations and exposes them to user programs. Most of the user-facing API is covered, as well as internal code. New command-line flags --no-header and --no-summary A warning is now shown when an unknown key is read from a config INI file. The --strict-config flag has been added to treat these warnings as errors. New required_plugins configuration option allows the user to specify a list of plugins, including version information, that are required for pytest to run. An error is raised if any required plugins are not found when running pytest. Improvements You can now pass output to things like less and head that close the pipe passed to them. thank you!!! Improved precision of test durations measurement. use --durations=10 -vv to capture and show durations Rich comparison for dataclasses and attrs-classes is now recursive. pytest --version now displays just the pytest version, while pytest --version --version displays more verbose information including plugins. --junitxml now includes the exception cause in the message XML attribute for failures during setup and teardown. Improved Documentation Add a note about --strict and --strict-markers and the preference for the latter one. Explain indirect parametrization and markers for fixtures. Bug Fixes Deprecations Trivial/Internal Changes Breaking Changes you might need to care about before upgrading PytestDeprecationWarning are now errors by default. Check the deprecations and removals (https://docs.pytest.org/en/latest/deprecations.html) page if you are curious. -k and -m internals were rewritten to stop using eval(), this results in a few slight changes but overall makes them much more consistent testdir.run().parseoutcomes() now always returns the parsed nouns in plural form. I'd say that's an improvement Special Guest: Anthony Sottile.

125: pytest 6 - Anthony Sottile

pip is the package installer for Python. Often, when you run pip, especially the first time in a new virtual environment, you will see something like: WARNING: You are using pip version 20.1.1; however, version 20.2 is available. You should consider upgrading via the 'python -m pip install --upgrade pip' command. And you should. Because 20.2 has a new dependency resolver. Get in the habit, until October, of replacing pip install with pip install --use-feature=2020-resolver. This flag is new in the 20.2 release. This new pip dependency resolver is the result of a lot of work. Five of the people involved with this work are joining the show today: Bernard Tyers, Nicole Harris, Paul Moore, Pradyun Gedam, and Tzu-ping Chung. We talk about: * pip dependency resolver changes * user experience research and testing * crafting good error messages * efforts to improve the test suite * testing pip with pytest * some of the difficulties with testing pip * working with a team on a large project * working with a large code base * bringing new developers into a large project Special Guests: Bernard Tyers, Nicole Harris, Paul Moore, Pradyun Gedam, and Tzu-ping Chung.

124: pip dependency resolver changes

Test & Code is a weekly podcast hosted by Brian Okken. The show covers a wide array of topics including software engineering, development, testing, Python programming, and many related topics. When we get into the implementation specifics, that's usually Python, such as Python packaging, tox, pytest, and unittest. However, well over half of the topics are language agnostic, such as data science, DevOps, TDD, public speaking, mentoring, feature testing, NoSQL databases, end to end testing, automation, continuous integration, development methods, Selenium, the testing pyramid, and DevOps.

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Test & Code: Python Software Testing & Engineering

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