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I don't think unit tests are even the only form of testing prescribed by TDD, although it might've been what Mr. Beck had in mind back then. It's test driven de

I don't think unit tests are even the only form of testing prescribed by TDD, although it might've been what Mr. Beck had in mind back then. It's test driven development: invalidate implementations that don't implement your specification! Unit tests are, unfortunately, not sufficient at expressing complex invariant properties and assumptions. So try property based tests. You can't even have Continuous Integration without integration tests and you shouldn't be practicing Continuous Delivery without an effective testing strategy. How else can you ship dozens of delta changes to production on a heavily trafficked site without taking down the service? Not sure what to test? System hard to describe? Try formal methods. Tools like TLA+ or Alloy are great at helping us understand systems with global or temporal properties and complex behaviors. GUIs? There are nascent projects to add property testing to the browser [0]. There are tools to model GUIs [1]. There are books to use property based testing on GUI-driven applications. It can be done [2]. It requires effort from a test driven development team. I've seen QA Teams ruin businesses. When they act as gate keepers to the production environment releases slow to a crawl, issues run unchecked for weeks as high-level e2e test results are inefficiently communicated and the source of the problem is rarely obvious or known. Developers then have to dedicate time to helping testers investigate poorly understood test failures which requires more developers to pick up the slack. More features requires more testers. And the cycle slows down releases to the point that your horizon for even a basic new feature is a couple months at best. [0] https://webcheck.tools/ https://webcheck.tools/ [1] https://sketch.systems/ https://sketch.systems/ [2] https://leanpub.com/property-based-testing-in-a-screencast-editor https://leanpub.com/property-based-testing-in-a-screencast-e...

pydry 6y ago
>Unit tests are, unfortunately, not sufficient at expressing complex invariant properties and assumptions. They're also insufficient at clearly articulating most specifications. Unit tests allow you to express clearly specifications in the form of code APIs that don't have complex side effects. They suck at everything else (that's about 90% of all real code). Good luck converting that user mock up into a unit test. TDD is technically possible with UAT - it just requires sophisticated tooling that is, most of the time, more expensive to build and maintain than your actual app. It also requires love/investment to make it fast enough. Its not worth it most of the time and TDD with unit tests is an insufficient salve. Hence QA teams and developers who have a feedback loop that involves running the code and clicking stuff.

pydry 6y ago

>Unit tests are, unfortunately, not sufficient at expressing complex invariant properties and assumptions. They're also insufficient at clearly articulating most specifications. Unit tests allow you to express clearly specifications in the form of code APIs that don't have complex side effects. They suck at everything else (that's about 90% of all real code). Good luck converting that user mock up into a unit test. TDD is technically possible with UAT - it just requires sophisticated tooling that is, most of the time, more expensive to build and maintain than your actual app. It also requires love/investment to make it fast enough. Its not worth it most of the time and TDD with unit tests is an insufficient salve. Hence QA teams and developers who have a feedback loop that involves running the code and clicking stuff.