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From: Brendan Higgins <brendanhiggins@google.com>
To: mcgrof@kernel.org
Cc: Greg KH <gregkh@linuxfoundation.org>,
	Kees Cook <keescook@google.com>,
	shuah@kernel.org, Joel Stanley <joel@jms.id.au>,
	mpe@ellerman.id.au, joe@perches.com, brakmo@fb.com,
	rostedt@goodmis.org, Tim.Bird@sony.com, khilman@baylibre.com,
	Julia Lawall <julia.lawall@lip6.fr>,
	linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	jdike@addtoit.com, richard@nod.at, linux-um@lists.infradead.org,
	Daniel Vetter <daniel@ffwll.ch>,
	dri-devel@lists.freedesktop.org, Rob Herring <robh@kernel.org>,
	dan.j.williams@intel.com, linux-nvdimm@lists.01.org,
	kieran.bingham@ideasonboard.com,
	Frank Rowand <frowand.list@gmail.com>,
	Knut Omang <knut.omang@oracle.com>,
	Sasha Levin <Alexander.Levin@microsoft.com>,
	levinsasha
Subject: Re: [RFC v3 01/19] kunit: test: add KUnit test runner core
Date: Fri, 30 Nov 2018 17:51:11 -0800
Message-ID: <CAFd5g47t94RR78_sZ7Xr7ArDh+hJGYHNwmmG2HJb7AW+i=u3ew@mail.gmail.com> (raw)
In-Reply-To: <20181130031438.GQ4922@garbanzo.do-not-panic.com>

On Thu, Nov 29, 2018 at 7:14 PM Luis Chamberlain <mcgrof@kernel.org> wrote:
>
> On Wed, Nov 28, 2018 at 11:36:18AM -0800, Brendan Higgins wrote:
> > +#define module_test(module) \
> > +             static int module_kunit_init##module(void) \
> > +             { \
> > +                     return kunit_run_tests(&module); \
> > +             } \
> > +             late_initcall(module_kunit_init##module)
>
> Here in lies an assumption that suffices. I'm inclined to believe we
> need new initcall level here so to ensure we *do* run after all the
> respective kernels iniut calls. Otherwise we're left at the whims of
> link order for kunit. For instance if a kunit test relies on frameworks
> which are also late_initcall() we'd have complete incompatibility with
> anything linked *after* kunit.

Yep, I have some patches that address this, but I thought this is
sufficient for the initial patchset (I figured that's the type of
thing that people will have opinions about so best to get it out of
the critical path). Do you want me to add those in the next revision?

>
> > diff --git a/kunit/Kconfig b/kunit/Kconfig
> > new file mode 100644
> > index 0000000000000..49b44c4f6630a
> > --- /dev/null
> > +++ b/kunit/Kconfig
> > @@ -0,0 +1,17 @@
> > +#
> > +# KUnit base configuration
> > +#
> > +
> > +menu "KUnit support"
> > +
> > +config KUNIT
> > +     bool "Enable support for unit tests (KUnit)"
> > +     depends on UML
>
> Consider using:
>
> if UML
>    ...
> endif
>
> That allows the depends to be done once.

If you want to eliminate depends, wouldn't it be best to have KUNIT
depend on whatever it needs, and then do `if KUNIT` below that? That
seems cleaner over the long term. Anyway, Kees actually asked me to
change it to the way it is now; I really don't care either way.

>
> > +     help
> > +       Enables support for kernel unit tests (KUnit), a lightweight unit
> > +       testing and mocking framework for the Linux kernel. These tests are
> > +       able to be run locally on a developer's workstation without a VM or
> > +       special hardware.
>
>
> Some mention of UML may be good here?

Good point.
>
> > For more information, please see
> > +       Documentation/kunit/
> > +
> > +endmenu
>
> I'm a bit conflicted here. This currently depends on UML but yet you
> noted on RFC v2 that your intention is to liberate kunit from UML and
> ideally allow unit tests to depend only on userspace. I've addressed
> tests using both selftests kernels drivers and also re-written kernel
> APIs to userspace to test there. I think we may need to live with both.

I am not entirely opposed. The greater isolation we can achieve, the
fewer dependencies, and barriers to setting up test fixtures the
better. I think the best way to do that in most cases is allowing
minimal test binaries to be built that have the absolute minimum
amount of code necessary to test the desired property. That being
said, integration tests are a thing and drawing a line between them
and unit tests is not always possible, so supporting other
architectures might be necessary.

>
> Then for the UML stuff, I think if we *really* accept that UML will
> always be a viable option we should probably consider now throwing these
> things under drivers/platform/uml/. This follows the pattern of arch
> specific drivers. Whether or not we end up with a complete userspace
> component independent of UML may implicate having a shared component
> somewhere else.

Fair enough. What specifically are you suggesting should go in
`drivers/platform/uml`? Just the bits that are completely tied to UML
or a concrete architecture?

>
> Likewise, I realize the goal is to *avoid* using a virtual machine for
> these tests, but would it in any way make sense to share kunit to be
> supported for other architectures to allow easier-to-write tests as
> well?

You are not the first person to ask for this.

For the vast majority of tests, I think we can (and consequently
should) make them run without any external dependencies. Doing so
makes it such that someone can run a test without knowing anything
about it, which allows you to do a lot of things. For one, I, as a
developer, don't have to hunt down somebody's QEMU patches, or
whatever. But it also means I, as someone maintaining part of the
kernel, can make nice test runners and build things like presubmit
servers on top of them.

Nevertheless, I accept that there are things which are just easier to
do with hardware or a VM (for integration tests it is necessary).
Still, I think we need to make sure the vast majority of unit tests do
not depend on real hardware or a VM.

  reply index

Thread overview: 118+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-28 19:36 [RFC v3 00/19] kunit: introduce KUnit, the Linux kernel unit testing framework Brendan Higgins
2018-11-28 19:36 ` [RFC v3 01/19] kunit: test: add KUnit test runner core Brendan Higgins
2018-11-30  3:14   ` Luis Chamberlain
2018-12-01  1:51     ` Brendan Higgins [this message]
2018-12-01  2:57       ` Luis Chamberlain
2018-12-05 13:15     ` Anton Ivanov
2018-12-05 14:45       ` Arnd Bergmann
2018-12-05 14:49         ` Anton Ivanov
2018-11-30  3:28   ` Luis Chamberlain
     [not found]     ` <20181130032802.GG18410-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-01  2:08       ` Brendan Higgins
2018-12-01  3:10         ` Luis Chamberlain
     [not found]           ` <20181201031049.GL28501-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-03 22:47             ` Brendan Higgins
2018-12-01  3:02   ` Luis Chamberlain
2018-11-28 19:36 ` [RFC v3 10/19] kunit: test: add test managed resource tests Brendan Higgins
     [not found] ` <20181128193636.254378-1-brendanhiggins-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2018-11-28 19:36   ` [RFC v3 02/19] kunit: test: add test resource management API Brendan Higgins
2018-11-28 19:36   ` [RFC v3 03/19] kunit: test: add string_stream a std::stream like string builder Brendan Higgins
2018-11-30  3:29     ` Luis Chamberlain
2018-12-01  2:14       ` Brendan Higgins
2018-12-01  3:12         ` Luis Chamberlain
2018-12-03 10:55       ` Petr Mladek
2018-12-04  0:35         ` Brendan Higgins
2018-11-28 19:36   ` [RFC v3 04/19] kunit: test: add test_stream a std::stream like logger Brendan Higgins
2018-11-28 19:36   ` [RFC v3 05/19] kunit: test: add the concept of expectations Brendan Higgins
2018-11-28 19:36   ` [RFC v3 06/19] arch: um: enable running kunit from User Mode Linux Brendan Higgins
2018-11-28 21:26     ` Rob Herring
2018-11-30  3:37       ` Luis Chamberlain
2018-11-30 14:05         ` Rob Herring
2018-11-30 18:22           ` Luis Chamberlain
     [not found]             ` <20181130182203.GS18410-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-03 23:22               ` Brendan Higgins
2018-11-30  3:30     ` Luis Chamberlain
2018-11-28 19:36   ` [RFC v3 07/19] kunit: test: add initial tests Brendan Higgins
2018-11-30  3:40     ` Luis Chamberlain
2018-12-03 23:26       ` Brendan Higgins
2018-12-03 23:43         ` Luis Chamberlain
2018-11-28 19:36   ` [RFC v3 08/19] arch: um: add shim to trap to allow installing a fault catcher for tests Brendan Higgins
2018-11-30  3:34     ` Luis Chamberlain
     [not found]       ` <20181130033429.GK18410-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-03 23:34         ` Brendan Higgins
     [not found]           ` <CAFd5g45+MAVaSW8HN9x57Y8Um=TV1Oa=-K8yExPBS-4KjLyciQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-12-03 23:46             ` Luis Chamberlain
     [not found]               ` <20181203234628.GR28501-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-04  0:44                 ` Brendan Higgins
2018-11-30  3:41     ` Luis Chamberlain
2018-12-03 23:37       ` Brendan Higgins
2018-11-28 19:36   ` [RFC v3 09/19] kunit: test: add the concept of assertions Brendan Higgins
2018-11-28 19:36   ` [RFC v3 11/19] kunit: add Python libraries for handing KUnit config and kernel Brendan Higgins
2018-11-29 13:54     ` Kieran Bingham
     [not found]       ` <841cf4ae-501b-05ae-5863-a51010709b67-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
2018-12-03 23:48         ` Brendan Higgins
2018-12-04 20:47           ` Luis Chamberlain
2018-12-06 12:32             ` Kieran Bingham
2018-12-06 15:37               ` Matthew Wilcox
2018-12-07 11:30                 ` Kieran Bingham
2018-12-11 14:09                 ` Petr Mladek
2018-12-11 14:41                   ` Steven Rostedt
2018-12-11 17:01                     ` Anton Ivanov
2019-02-09  0:40                       ` Brendan Higgins
2018-12-07  1:05               ` Luis Chamberlain
2018-12-07 18:35               ` Kent Overstreet
2018-11-30  3:44     ` Luis Chamberlain
2018-12-03 23:50       ` Brendan Higgins
2018-12-04 20:48         ` Luis Chamberlain
2018-11-28 19:36   ` [RFC v3 12/19] kunit: add KUnit wrapper script and simple output parser Brendan Higgins
2018-11-28 19:36   ` [RFC v3 13/19] kunit: improve output from python wrapper Brendan Higgins
2018-11-28 19:36   ` [RFC v3 14/19] Documentation: kunit: add documentation for KUnit Brendan Higgins
2018-11-29 13:56     ` Kieran Bingham
2018-11-30  3:45       ` Luis Chamberlain
     [not found]         ` <20181130034525.GP18410-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-03 23:53           ` Brendan Higgins
2018-12-06 12:16             ` Kieran Bingham
2019-02-09  0:56               ` Brendan Higgins
2019-02-11 12:16                 ` Kieran Bingham
2019-02-12 22:10                   ` Brendan Higgins
2019-02-13 21:55                     ` Kieran Bingham
2019-02-14  0:17                       ` Brendan Higgins
2019-02-14 17:26                         ` Luis Chamberlain
2019-02-14 22:07                           ` Brendan Higgins
2018-11-28 19:36   ` [RFC v3 15/19] MAINTAINERS: add entry for KUnit the unit testing framework Brendan Higgins
2018-11-28 19:36   ` [RFC v3 17/19] of: unittest: migrate tests to run on KUnit Brendan Higgins
2018-11-28 20:56     ` Rob Herring
2018-11-30  0:39       ` Randy Dunlap
     [not found]         ` <18814973-8f0a-4647-a097-fcc3dc0b3cd3-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-12-04  0:13           ` Brendan Higgins
2018-12-04 13:40             ` Rob Herring
     [not found]               ` <CAL_JsqL_PivQbrJFEusdKAy-2EQtKL3OHbmyYSK9bzuTOQegqA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-12-05 23:42                 ` Brendan Higgins
2018-12-07  0:41                   ` Rob Herring
2018-12-04  0:08       ` Brendan Higgins
2019-02-13  1:44       ` Brendan Higgins
2019-02-14 20:10         ` Rob Herring
2019-02-14 21:52           ` Brendan Higgins
2019-02-18 22:56         ` Frank Rowand
2019-02-28  0:29           ` Brendan Higgins
2018-12-04 10:56     ` Frank Rowand
2018-11-28 19:36   ` [RFC v3 18/19] of: unittest: split out a couple of test cases from unittest Brendan Higgins
2018-12-04 10:58     ` Frank Rowand
2018-12-05 23:54       ` Brendan Higgins
2019-02-14 23:57         ` Frank Rowand
2019-02-15  0:56           ` Brendan Higgins
2019-02-15  2:05             ` Frank Rowand
2019-02-15 10:56               ` Brendan Higgins
2019-02-18 22:25                 ` Frank Rowand
2019-02-20 20:44                   ` Frank Rowand
2019-02-20 20:47                     ` Frank Rowand
2019-02-28  3:52                     ` Brendan Higgins
2019-03-22  0:22                       ` Frank Rowand
2019-03-22  1:30                         ` Brendan Higgins
2019-03-22  1:47                           ` Frank Rowand
2019-03-25 22:15                             ` Brendan Higgins
2019-09-20 16:57                           ` Rob Herring
2019-09-21 23:57                             ` Frank Rowand
2019-03-22  1:34                         ` Frank Rowand
2019-03-25 22:18                           ` Brendan Higgins
2018-11-28 19:36   ` [RFC v3 19/19] of: unittest: split up some super large test cases Brendan Higgins
2018-11-28 19:36 ` [RFC v3 16/19] arch: um: make UML unflatten device tree when testing Brendan Higgins
2018-11-28 21:16   ` Rob Herring
     [not found]     ` <CAL_JsqK5cG=QzMBFSZ31_-3ujnxqxv=jj3XYajbRLT7yWYZbfw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-12-04  0:00       ` Brendan Higgins
2018-11-30  3:46   ` Luis Chamberlain
2018-12-04  0:02     ` Brendan Higgins
2018-12-04 10:52 ` [RFC v3 00/19] kunit: introduce KUnit, the Linux kernel unit testing framework Frank Rowand
2018-12-04 11:40 ` Frank Rowand
2018-12-04 13:49   ` Rob Herring
2018-12-05 23:10     ` Brendan Higgins
2019-03-22  0:27       ` Frank Rowand
2019-03-25 22:04         ` Brendan Higgins

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