A Sixth Seam in TDD? - Python Testing, Test Doubles & Legacy Code at Kosli - Jon Jagger - ACCU 2025 скачать в хорошем качестве

A Sixth Seam in TDD? - Python Testing, Test Doubles & Legacy Code at Kosli - Jon Jagger - ACCU 2025

ACCU Membership: https://tinyurl.com/ydnfkcyn --- A Sixth Seam in TDD? - Python Testing, Test Doubles & Legacy Code at Kosli - Jon Jagger - ACCU 2025 Short Talks --- What if there's a sixth seam in test-driven development (TDD) that we’ve overlooked? In this lightning talk from ACCU 2025, Jon Jagger—creator of Cyber-Dojo and co-founder at Kosli—explores a novel idea in Python testing: an auto cache seam that enhances test performance and stability. This talk dives into Python unit testing techniques using pytest, exploring how to leverage a cache generated at the seam to replay test results, reducing flaky tests and improving CI feedback speed. If you're familiar with test doubles—dummy, stub, spy, mock, and fake—you’ll appreciate this perspective on introducing what might be a sixth test double. By using test seams (as described by Michael Feathers in Working Effectively with Legacy Code), Jon introduces a caching mechanism that acts like a combination of stub and spy, enabling tests to either replay results from cache or regenerate them only when necessary. The implementation uses pytest fixtures with autouse=True and a clever use of `pickle` files to cache the data. This approach addresses the growing complexity in legacy code and is especially useful for dealing with flaky tests. Runtime failures are handled gracefully using the runtime-failures library, ensuring reliability even when the system under test is unstable. Learn how Kosli integrates this strategy into its real-world pipelines and discover how you can adopt similar patterns in your own test driven development workflow. Whether you're working on legacy systems, refactoring large Python codebases, or trying to reduce CI runtime, this talk is packed with valuable, actionable insights. Keywords: python testing, unit testing, test doubles, tdd, test driven development, pytest, legacy code, flaky tests, runtime failures python, seam in unit testing, kosli, jon jagger, accu 2025 Chapters 0:00 - Introduction and talk title correction 0:21 - Dylan Thomas reference and personal intro 0:59 - The idea: caching at seams in test code 1:14 - What is a seam? (Michael Feathers definition) 1:50 - Test doubles overview: dummy, stub, spy, mock, fake 2:38 - The sixth seam: auto cache concept 3:00 - Python implementation at Kosli 3:44 - pytest fixture with autouse 4:26 - Using the cache at the seam 4:47 - Replay vs rebuild logic 5:05 - Handling flaky tests with runtime-failures Slides: https://accu.org/conf-previous/accu2025/ Join think-cell as a C++ Developer and work on cutting-edge challenges with a focus on code excellence, innovation, and working alongside an international team of experts — apply now to be part of a team shaping the future of business presentations. https://www.think-cell.com/en/career --- Jon Jagger Husband, Dad, Grandad. Coding and Testing for 30 years (hex). Built cyber-dojo. Love fishing. Head of Software at Kosli. Video Sponsored By JetBrains --- The ACCU Conference is the annual conference of the ACCU membership, but is open to any and all who wish to attend. The tagline for the ACCU is 'Professionalism in Programming', which captures the whole spectrum of programming languages, tools, techniques and processes involved in advancing our craft. While there remains a core of C and C++ - with many members participating in respective ISO standards bodies - the conference, like the organisation, embraces other language ecosystems and you should expect to see sessions on C#, D, F#, Go, Javascript, Haskell, Java, Kotlin, Lisp, Python, Ruby, Rust, Swift and more.The ACCU Conference is a conference by programmers for programmers about programming. Discounted rates for members. ACCU Membership: https://tinyurl.com/ydnfkcyn 2025 Program: https://accu.org/conf-previous/accu2025/ https://accu.org https://www.accuconference.org/ https://mastodon.social/@ACCUConf   / accu-conference   https://bsky.app/profile/accuconf.bsk...   / accuorg     / accuconf   --- YouTube Videos Filmed, Edited & Optimised by Digital Medium: https://events.digital-medium.co.uk #accuconf #python #pythonprogramming #pythonprogramminglanguage #code #programming #softwaredevelopment #softwareengineer #programmingconcepts #coding #programmingtutorial #software #softwareengineering #learnpython