QA writing unit tests for devs is not “traditional” - it’s a signal to leave the place ASAP.
As an engineer, you’re expected to write, review, and test code. We simply shuffle responsibilities such that you usually test other engineers’ code and not your own (there is some discretion involved - for very small changes we often write or tweak the test ourselves)
Yeah that's why I put traditional in quotes. I guess, rather outdated? But whatever.. the question is how is this different? The engineer who writes the code still not the one who tests it, am I misunderstanding this?
Ack. You’re right in that the engineer who writes the code is not the one who writes the test, but recall that all this happens at the code-review phase.
When QA finds holes when writing unit tests (rare), it goes on a backlog. For us, if the reviewer finds a bug or finds the code not very testable, your code isn’t getting merged. We catch both errors and design issues (especially premature optimizations and overly large API surface area) very early. Habitually, our engineers write simple, well-documented code with concise APIs at a well-defined level of abstraction (we also follow some other heuristics to make this obvious) on the first revision, so we rarely (6 total in the last 3 months if I’m querying correctly) have more than two revisions despite the additional ‘write tests’ step from the reviewer.
We found that engineers take great joy in trying to break others’ code, but also enjoy collaborating in a scratch-each-others-backs way when they get to give useful feedback. We’ve been able to channel that into great test coverage (around 99% FWIW). We’re pre-launch, so ultimately we may uncover bugs in production at the same rate as traditional code reviewing shops ¯\_()_/¯, but we’ve had close to zero issues needing manual intervention in months of early user testing.
As an engineer, you’re expected to write, review, and test code. We simply shuffle responsibilities such that you usually test other engineers’ code and not your own (there is some discretion involved - for very small changes we often write or tweak the test ourselves)