Messages in this thread | | | From | Daniel Latypov <> | Date | Sat, 2 Oct 2021 11:11:15 -0700 | Subject | Re: [PATCH] kunit: mock: add support for function mocks with no parameters |
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On Sat, Oct 2, 2021 at 11:09 AM Daniel Latypov <dlatypov@google.com> wrote: > > On Mon, Sep 27, 2021 at 9:44 AM Daniel Latypov <dlatypov@google.com> wrote: > > > > [2] > > On Sat, Sep 25, 2021 at 12:30 PM Marcelo Schmitt > > <marcelo.schmitt1@gmail.com> wrote: > > > > > > Hi Daniel, > > > > > > Thanks for your review. > > > > > > On 09/21, Daniel Latypov wrote: > > > > On Sat, Sep 18, 2021 at 12:44 PM Marcelo Schmitt > > > > <marcelo.schmitt1@gmail.com> wrote: > > > > > > > > > > Function mocks defined with DEFINE_FUNCTION_MOCK(...) do not support > > > > > empty parameters list due to strict function prototypes enforcement > > > > > (-Werror=strict-prototypes). Add support for function mocks with no > > > > > parameters by adding checks to declare strict function prototypes when > > > > > an empty param list is provided. > > > > > Further, add an expectation to test that the generated code works. > > > > > > > > > > Co-developed-by: Anderson Reis Rosa <andersonreisrosa@gmail.com> > > > > > Signed-off-by: Anderson Reis Rosa <andersonreisrosa@gmail.com> > > > > > Signed-off-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com> > > > > > > > > Meta: kunit/alpha/master isn't really maintained anymore. > > > > I think David and myself having some commits from this year might give > > > > the wrong impression. > > > > But all of my patches in 2021 were to make it easier to get people to > > > > *move away* from kunit/alpha/master ;) > > > > > > We can't submit it upstream because the mock stuff isn't there yet. > > > By the way, as nothing from mocking is upstream and kunit/alpha/master is > > > being frozen somewhat, what tree/branch should we base our work on if we > > > decide to develop more on the mocking framework? > > > I recall the branch with the POC for mocking was at > > > https://kunit-review.googlesource.com/c/linux/+/1114 > > > Should we use this branch to base future work on mocking? > > > Or will the mocking framework be discontinued? > > > > All the mocking stuff is in limbo at the moment. > > The v2 of the class mocking RFC was sent out Oct 2020, > > https://lore.kernel.org/linux-kselftest/20201012222050.999431-1-dlatypov@google.com/ > > > > Until we have user interest in mocking support, that RFC will likely > > just sit there. > > Or maybe we scrap it and just introduce the functionality piece by piece. > > > > There's https://kunit.dev/mocking.html which talks about how one can > > implement mocking on their own, or (better yet) write fakes while > > leveraging KUnit. > > If we start seeing adoption of that, we can start factoring out > > functionality into shared code as needed, e.g. support for saying a > > mock should be called N times, then maybe gradually the parameter > > matchers and return values, etc. > > > > I missed it, but I know David and Brendan talked a bit about this in > > their recent LPC talk, https://youtu.be/Y_minEhZNm8?t=15905 > > > > > > > > Sorry for asking so many questions. We just want to help to enhance KUnit. > > > > No worries, and we really appreciate it. > > > > > We can work on something else besides mocking if it makes more sense to the > > > project. > > > > Mocking doesn't feel like an area where we can expect to see progress right now. > > In terms of other KUnit features we know would be useful now, I think > > it's mostly just [1] and [2], which hopefully will land in 5.16. > > To be clear, if anyone thinks up a useful feature, that'd be great. > I personally am just out of ideas at the moment, and I think so are > Brendan and David. > > We'd want to prioritize features that can improve existing tests or > unblock known new tests. > Mocking in the alpha version of KUnit is a case where a feature > sounded really good on paper and had a bunch of bells and whistles > (e.g. strict/nice/naggy mocks support, etc.) but was perhaps > overengineered and thus failed to find a home upstream. > > But I just thought of a few more things we could do in the kunit.py script. > I think we have more room for improvement there than in the in-kernel > part of KUnit right now, but I assume it's the more boring part for > most people. > > One thing I'd really like to see is getting code coverage to work in > kunit.py while using QEMU. > We have a process for doing so under UML here: > https://lore.kernel.org/linux-kselftest/20210901190623.315736-1-rmoar@google.com/
wrong copy-paste, meant https://www.kernel.org/doc/html/latest/dev-tools/kunit/running_tips.html#generating-code-coverage-reports-under-uml
> UML actually uses a different coverage implementation than normal, so > there's a few things that would need to change. > > We can build and run against "normal" coverage kernels pretty easily: > > $ cat >qemu_coverage_kunitconfig <<EOF > CONFIG_KUNIT=y > CONFIG_KUNIT_EXAMPLE_TEST=y > CONFIG_GCOV_KERNEL=y > CONFIG_DEBUG_FS=y > CONFIG_GCOV_PROFILE_ALL=y > EOF > $ ./tools/testing/kunit/kunit.py run --arch=x86_64 > --kunitconfig=qemu_coverage_kunitconfig > > The problem is we'd need to copy the coverage data off the VM instead > of just letting it shutdown when tests are done. > If we had a userspace running, we'd basically do something like > $ scp -r user@vm:/sys/kernel/debug/gcov . > <some stuff to get these files in the right spot under .kunit/> > <then we'd run lcov and genhtml, just like we do for UML> > > Normal KUnit tests definitely don't want to have to have the overhead > of running a userspace, so the implementation might look like a > "--qemu_coverage" flag, or maybe a set of generic flags that would > give a user enough control over the VM to do this. > Or maybe the right answer is to not involve kunit.py at all. > > Not sure if that sounds interesting to you or anyone. > > > > > I think right now we probably need more tests written to have a better > > idea of what else we could/should do. > > Partly because of that, David is trying to get the ball rolling on > > testing ext4. We're also hopeful that it'll be easier to add tests if > > adjacent code is already tested (sharing fakes, conventions, ability > > to copy-paste, etc.). > > > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git/commit/?h=kunit&id=3b29021ddd10cfb6b2565c623595bd3b02036f33 > > [2] https://lore.kernel.org/linux-kselftest/20210909001037.2842954-1-dlatypov@google.com/ > > > >
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