Re: [PATCH linux-kselftest/test v2] ext4: add kunit test for decoding extended timestamps

Iurii Zaikin
2019-10-17T23:08:16Z

> Having the ability to take test data doesn't make it non-deterministic
> though. It just means that if user wants to test with a different set
> of data, there is no need to recompile the test. This could be helpful
> to test cases the test write didn't think about.
>
Again, unit tests are not meant to be babysat. They are intended to become
a part of the codebase and be run against every proposed change to ensure
the change doesn't break anything.
The whole process is supposed to be fully automated.
Imagine a KUnit test run for all tests that gets kicked off as soon as a patch
shows up in Patchwork and the maintainers getting the test run results.
If you can think of a test that the change author didn't for a new corner case,
then you as the maintainer ask the change author to add such test.
Or if some corner case comes up as a result of a bug then the new case is
submitted with the fix.
This is how unit testing is deployed in the larger software world. In the most
enlightened places a change will not be accepted unless it's accompanied by
the unit tests that offer good coverage for the possible inputs and code paths.
A change that breaks existing tests is either incorrect and has to be fixed or
the existing tests need to be updated for the behavior change.