Re: [RFC] Create test script(s?) for regression testing

[Hans Verkuil <hverkuil@xs4all.nl>]

On 11/06/2018 08:58 PM, Laurent Pinchart wrote:
> Hi Hans,
> 
> On Tuesday, 6 November 2018 15:56:34 EET Hans Verkuil wrote:
>> On 11/06/18 14:12, Laurent Pinchart wrote:
>>> On Tuesday, 6 November 2018 13:36:55 EET Sakari Ailus wrote:
>>>> On Tue, Nov 06, 2018 at 09:37:07AM +0100, Hans Verkuil wrote:
>>>>> Hi all,
>>>>>
>>>>> After the media summit (heavy on test discussions) and the V4L2 event
>>>>> regression we just found it is clear we need to do a better job with
>>>>> testing.
>>>>>
>>>>> All the pieces are in place, so what is needed is to combine it and
>>>>> create a script that anyone of us as core developers can run to check
>>>>> for regressions. The same script can be run as part of the kernelci
>>>>> regression testing.
>>>>
>>>> I'd say that *some* pieces are in place. Of course, the more there is,
>>>> the better.
>>>>
>>>> The more there are tests, the more important it would be they're
>>>> automated, preferrably without the developer having to run them on his/
>>>> her own machine.
>>>
>>> From my experience with testing, it's important to have both a core set of
>>> tests (a.k.a. smoke tests) that can easily be run on developers' machines,
>>> and extended tests that can be offloaded to a shared testing
>>> infrastructure (but possibly also run locally if desired).
>>
>> That was my idea as well for the longer term. First step is to do the basic
>> smoke tests (i.e. run compliance tests, do some (limited) streaming test).
>>
>> There are more extensive (and longer running) tests that can be done, but
>> that's something to look at later.
>>
>>>>> We have four virtual drivers: vivid, vim2m, vimc and vicodec. The last
>>>>> one is IMHO not quite good enough yet for testing: it is not fully
>>>>> compliant to the upcoming stateful codec spec. Work for that is planned
>>>>> as part of an Outreachy project.
>>>>>
>>>>> My idea is to create a script that is maintained as part of v4l-utils
>>>>> that loads the drivers and runs v4l2-compliance and possibly other tests
>>>>> against the virtual drivers.
>>>>
>>>> How about spending a little time to pick a suitable framework for running
>>>> the tests? It could be useful to get more informative reports than just
>>>> pass / fail.
>>>
>>> We should keep in mind that other tests will be added later, and the test
>>> framework should make that easy.
>>
>> Since we want to be able to run this on kernelci.org, I think it makes sense
>> to let the kernelci folks (Hi Ezequiel!) decide this.
> 
> KernelCI isn't the only test infrastructure out there, so let's not forget 
> about the other ones.

True, but they are putting time and money into this, so they get to choose as
far as I am concerned :-)

If others are interested and willing to put up time and money, they should let
themselves be known.

I'm not going to work on such an integration, although I happily accept patches.

> 
>> As a developer all I need is a script to run smoke tests so I can catch most
>> regressions (you never catch all).
>>
>> I'm happy to work with them to make any changes to compliance tools and
>> scripts so they fit better into their test framework.
>>
>> The one key requirement to all this is that you should be able to run these
>> tests without dependencies to all sorts of external packages/libraries.
> 
> v4l-utils already has a set of dependencies, but those are largely manageable. 
> For v4l2-compliance we'll install libv4l, which depends on libjpeg.

That's already too much. You can manually build v4l2-compliance with no dependencies
whatsoever, but we're missing a Makefile target for that. It's been useful for
embedded systems with poor cross-compile environments.

It is really very useful to be able to compile those core utilities with no
external libraries other than glibc. You obviously will loose some functionality
when you compile it that way.

These utilities are not like a typical application. I really don't care how many
libraries are linked in by e.g. qv4l2, xawtv, etc. But for v4l2-ctl, v4l2-compliance,
cec-ctl/follower/compliance (and probably a few others as well) you want a minimum
of dependencies so you can run them everywhere, even with the crappiest toolchains
or cross-compile environments.

> 
>>> Regarding the test output, many formats exist (see
>>> https://testanything.org/ and
>>> https://chromium.googlesource.com/chromium/src/+/master/docs/testing/
>>> json_test_results_format.md for instance), we should pick one of the
>>> leading industry standards (what those standards are still needs to be
>>> researched  :-)).
>>>
>>>> Do note that for different hardware the tests would be likely different
>>>> as well although there are classes of devices for which the exact same
>>>> tests would be applicable.
>>>
>>> See http://git.ideasonboard.com/renesas/vsp-tests.git for an example of
>>> device-specific tests. I think some of that could be generalized.
>>>
>>>>> It should be simple to use and require very little in the way of
>>>>> dependencies. Ideally no dependencies other than what is in v4l-utils so
>>>>> it can easily be run on an embedded system as well.
>>>>>
>>>>> For a 64-bit kernel it should run the tests both with 32-bit and 64-bit
>>>>> applications.
>>>>>
>>>>> It should also test with both single and multiplanar modes where
>>>>> available.
>>>>>
>>>>> Since vivid emulates CEC as well, it should run CEC tests too.
>>>>>
>>>>> As core developers we should have an environment where we can easily
>>>>> test our patches with this script (I use a VM for that).
>>>>>
>>>>> I think maintaining the script (or perhaps scripts) in v4l-utils is best
>>>>> since that keeps it in sync with the latest kernel and v4l-utils
>>>>> developments.
>>>>
>>>> Makes sense --- and that can be always changed later on if there's a need
>>>> to.
>>>
>>> I wonder whether that would be best going forward, especially if we want
>>> to add more tests. Wouldn't a v4l-tests project make sense ?
>>
>> Let's see what happens. The more repos you have, the harder it becomes to
>> keep everything in sync with the latest kernel code.
> 
> Why is that ? How would a v4l-tests repository make it more difficult ?

Right now whenever we update the uAPI in the kernel we run 'make sync-with-kernel'
in v4l-utils to sync it to the latest kernel code. We only do this for this repo,
and adding a new repo where you have to do that will just complicate matters and
make it more likely you'll forget. I don't see a good reason to create a new repo
to store the test code.

However, I do think we might want to create a new repo to store video test
sequences (something I expect to see when we start on testing codecs).

It's IMHO a bad idea to add many MBs of video files to v4l-utils.

> 
>> My experience is that if you want to have good tests, then writing tests
>> should be as easy as possible. Keep dependencies at an absolute minimum.
> 
> To make it as easy as possible we need to provide high-level APIs, so 
> dependencies will be unavoidable. I found for instance that Python bindings 
> were very useful to write tests for DRM/KMS (using libkmsxx), and I plan to 
> have a look at Python bindings for V4L2.

Let's just start with simple smoke tests. Python bindings etc. are something
for the future. Nobody has the time to work on that anyway.

> 
>> Let's be honest, we (well, mainly me) are doing these tests as a side job,
>> it's not our main focus.
> 
> That's a mindset that needs to evolve :-)

I want to be more aggressive with this: new APIs will need patches to v4l-utils
as well before they can be accepted, and ideally new tests.

And hopefully the kernelci project will lead to some improvements as well.

> 
>> Anything that makes writing tests more painful is bad and just gets in the
>> way.
> 
> I don't see any disagreement on this. What makes it easy to write tests will 
> however be much more prone to arguments.
> 

Since I'm pretty much the only one who has been writing tests, I'd say that I
can make a good argument :-)

Regards,

	Hans