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Are Your Tests Slowing You Down?
Trisha Gee
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https://trishagee.com/books/
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Gradle is Pioneering DPE
Developer Productivity Engineering
is a software development practice
to maximise developer productivity
and happiness.
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Tests Make You More Productive?
Tests Make You More Productive
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So it’s OK not to write tests, right?
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“Testing is Xanax for programmers, it’s an anxiety
reducing technique.”
https://youtu.be/guycIP56YeY
Kent Beck
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Caveats
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RATED 6+
because apparently 5-year-olds fall asleep during the presentation
Some flashing GIF sequences may affect photosensitive viewers
This program contains product placement
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“Nothing is ever really lost to us as long as we
remember it.”
L.M. Montgomery
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What slows down your testing?
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1. Writing Tests Takes Time
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“Trisha, you’re actually a tester”
Liz Keogh (@lunivore)
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Use Your IDE
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Buy My Book!
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AI Will Make You Super Productive
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Beware, AI lies to you
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Bring a friend
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“We recommend that the developers, who are good at
writing efficient, maintainable code, work together
with the testers, who are good at specifying test cases,
to automate tests.”
Agile Testing Condensed: A Brief Introduction
Lisa Crispin, Janet Gregory
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https://bit.ly/3RG85vc
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“Creativity is a wild mind and a disciplined eye.”
Dorothy Parker
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Invest the time in writing to save time troubleshooting
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2. Troubleshooting Takes Time
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What is this test anyway?
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Is it the test that’s wrong, or
production code?
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Let me see…
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Let me see…
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Aim for fast feedback and easy
reproduction
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“99.9% of the time the best way to troubleshoot a test
is to re-write it so it’s smaller and faster.”
Israel Boza Rodriguez (@IsraKaos)
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Flaky Tests
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I have made the decision to trust you
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I have made the decision to trust you
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Fix your flaky tests!!!
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https://youtu.be/vHBzZHE4tJ0
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3. Running Tests Takes Time
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How do you speed up your tests?
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Use a build cache
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Very effective for multi-module projects
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No cache: Full build required
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Build cache: Changing a leaf module
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Build cache: Changing a module’s implementation
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Build cache: Changing core implementation
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Remote Build Cache
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Run tests in parallel (local)
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Run tests in parallel (CI)
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Test Distribution
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Test Distribution Results
‑ ~50%
‑ ~50%
‑ ~50%
Doubling the number of executors cuts build time in half
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Netflix reduced a 62-minute test cycle time down to just under 5 minutes!
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Let’s use AI!
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“The test selection procedure selects fewer than a third
of the tests that would be selected on the basis of build
dependencies”
Predictive Test Selection - Meta Research
https://research.facebook.com/publications/predictive-test-selection/
Mateusz Machalica, Alex Samylkin, Meredith Porth, Satish Chandra
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Predictive Test Selection time savings
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But Trisha, I just have So Many Tests!
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“Yes, I regularly delete tests that no longer add unique
value.”
Angie Jones (@techgirl1908)
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Like any performance problem,
focus on the worst-performers first
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“Once things like databases become a hindrance,
optimise the testing loop, mock things out to run things
fast. You can run locally and you don't have all the same
infra dependencies as someone else.”
On DevEx, PaaS, and Testing in Production https://bit.ly/3ZA0uQM
Kelsey Hightower
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Look out for expensive setup and tear
down
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Respect your test code
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⬢ Separation of concerns
⬢ Encapsulation
⬢ SOLID
⬢ DRY
⬢ Descriptive naming
⬢ Modularisation
⬢ Designing for performance
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Tension between these ideals
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“Tidying is software design addressing you, your
relationship to your code, and ultimately your
relationship with yourself…. Tidying is geek self-care.”
Tidy First?
Kent Beck
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Summary
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Automate as much as possible
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There are solutions out there designed for exactly this problem
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There is a time investment in writing tests,
because there should be thinking involved
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“Your best and wisest refuge from all troubles is in your
science.”
Ada Lovelace
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Thank you!