[Starlingx-discuss] Unit tests first!!!

[Jeremy Stanley]

On 2020-01-31 19:25:55 +0000 (+0000), Wensley, Barton wrote:
[...]
> So... my advice is to write your unit tests up front whenever
> possible. This saves time vs. writing them after you have already
> done your hardware testing (or worse - after your review has been
> given a -1 due to missing unit tests). If you have questions about
> what unit tests would be expected for a particular change or how
> to write them, contact one of the cores for the project you are
> working on - they will be happy to help.

Speaking from personal experience, making changes to untested code
paths is harrowing. I have no idea whether the already existing code
even works, much less whether my change will make it better or
worse. I find it especially comforting to first submit tests for the
code I'm planning to alter. That way when I submit the code changes
I have proof that they either don't alter the tested behavior (if
they aren't supposed to, for example a refactoring), or I'm forced
to also include changes to the tests which reflect the tested
behaviors being altered. This is a huge help to reviewers as well,
since they can see immediately what behaviors are changing and
confirm those are expected.

So I second your advice to incorporate tests when proposing changes
which add new features/behaviors, but also strongly recommend adding
tests for previously untested code *in advance of* modifying it.
Including new tests in the same change as your behavior
modifications is too late to get full benefit from them.
-- 
Jeremy Stanley
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