Re: [PATCH v2 00/17] kunit: introduce KUnit, the Linux kernel unit testing framework

[Brendan Higgins <brendanhiggins@google.com>]

On Tue, May 14, 2019 at 02:05:05PM +0200, Daniel Vetter wrote:
> On Tue, May 14, 2019 at 8:04 AM Brendan Higgins
> <brendanhiggins@google.com> wrote:
> >
> > On Mon, May 13, 2019 at 04:44:51PM +0200, Daniel Vetter wrote:
> > > On Sat, May 11, 2019 at 01:33:44PM -0400, Theodore Ts'o wrote:
> > > > On Fri, May 10, 2019 at 02:12:40PM -0700, Frank Rowand wrote:
> > > > > However, the reply is incorrect.  Kselftest in-kernel tests (which
> > > > > is the context here) can be configured as built in instead of as
> > > > > a module, and built in a UML kernel.  The UML kernel can boot,
> > > > > running the in-kernel tests before UML attempts to invoke the
> > > > > init process.
> > > >
> > > > Um, Citation needed?
> > > >
> > > > I don't see any evidence for this in the kselftest documentation, nor
> > > > do I see any evidence of this in the kselftest Makefiles.
> > > >
> > > > There exists test modules in the kernel that run before the init
> > > > scripts run --- but that's not strictly speaking part of kselftests,
> > > > and do not have any kind of infrastructure.  As noted, the
> > > > kselftests_harness header file fundamentally assumes that you are
> > > > running test code in userspace.
> > >
> > > Yeah I really like the "no userspace required at all" design of kunit,
> > > while still collecting results in a well-defined way (unless the current
> > > self-test that just run when you load the module, with maybe some
> > > kselftest ad-hoc wrapper around to collect the results).
> > >
> > > What I want to do long-term is to run these kernel unit tests as part of
> > > the build-testing, most likely in gitlab (sooner or later, for drm.git
> >
> > Totally! This is part of the reason I have been insisting on a minimum
> > of UML compatibility for all unit tests. If you can suffiently constrain
> > the environment that is required for tests to run in, it makes it much
> > easier not only for a human to run your tests, but it also makes it a
> > lot easier for an automated service to be able to run your tests.
> >
> > I actually have a prototype presubmit already working on my
> > "stable/non-upstream" branch. You can checkout what presubmit results
> > look like here[1][2].
> 
> ug gerrit :-)

Yeah, yeah, I know, but it is a lot easier for me to get a project set
up here using Gerrit, when we already use that for a lot of other
projects.

Also, Gerrit has gotten a lot better over the last two years or so. Two
years ago, I wouldn't touch it with a ten foot pole. It's not so bad
anymore, at least if you are used to using a web UI to review code.

> > > only ofc). So that people get their pull requests (and patch series, we
> > > have some ideas to tie this into patchwork) automatically tested for this
> >
> > Might that be Snowpatch[3]? I talked to Russell, the creator of Snowpatch,
> > and he seemed pretty open to collaboration.
> >
> > Before I heard about Snowpatch, I had an intern write a translation
> > layer that made Prow (the presubmit service that I used in the prototype
> > above) work with LKML[4].
> 
> There's about 3-4 forks/clones of patchwork. snowpatch is one, we have
> a different one on freedesktop.org. It's a bit a mess :-/

Oh, I didn't realize that. I found your patchwork instance here[5], but
do you have a place where I can see the changes you have added to
support presubmit?

> > I am not married to either approach, but I think between the two of
> > them, most of the initial legwork has been done to make presubmit on
> > LKML a reality.
> 
> We do have presubmit CI working already with our freedesktop.org
> patchwork. The missing glue is just tying that into gitlab CI somehow
> (since we want to unify build testing more and make it easier for
> contributors to adjust things).

I checked out a couple of your projects on your patchwork instance: AMD
X.Org drivers, DRI devel, and Wayland. I saw the tab you added for
tests, but none of them actually had any test results. Can you point me
at one that does?

Cheers!

[5] https://patchwork.freedesktop.org/

> > > super basic stuff.
> >
> > I am really excited to hear back on what you think!
> >
> > Cheers!
> >
> > [1] https://kunit-review.googlesource.com/c/linux/+/1509/10#message-7bfa40efb132e15c8388755c273837559911425c
> > [2] https://kunit-review.googlesource.com/c/linux/+/1509/10#message-a6784496eafff442ac98fb068bf1a0f36ee73509
> > [3] https://developer.ibm.com/open/projects/snowpatch/
> > [4] https://kunit.googlesource.com/prow-lkml/
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