Re: [PATCH v2 12/17] kunit: tool: add Python wrappers for running KUnit tests

Brendan Higgins
2019-05-06T21:39:21Z

> On 5/3/19 4:14 PM, Brendan Higgins wrote:
> >> On 5/2/19 10:36 PM, Brendan Higgins wrote:
> >>> On Thu, May 2, 2019 at 6:45 PM Frank Rowand <frowand.list@gmail.com> wrote:
> >>>>
> >>>> On 5/2/19 4:45 PM, Brendan Higgins wrote:
> >>>>> On Thu, May 2, 2019 at 2:16 PM Frank Rowand <frowand.list@gmail.com> wrote:
> >>>>>>
> >>>>>> On 5/2/19 11:07 AM, Brendan Higgins wrote:
> >>>>>>> On Thu, May 2, 2019 at 4:02 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> >>>>>>>>
> >>>>>>>> On Wed, May 01, 2019 at 04:01:21PM -0700, Brendan Higgins wrote:
> >>>>>>>>> From: Felix Guo <felixguoxiuping@gmail.com>
> >>>>>>>>>
> >>>>>>>>> The ultimate goal is to create minimal isolated test binaries; in the
> >>>>>>>>> meantime we are using UML to provide the infrastructure to run tests, so
> >>>>>>>>> define an abstract way to configure and run tests that allow us to
> >>>>>>>>> change the context in which tests are built without affecting the user.
> >>>>>>>>> This also makes pretty and dynamic error reporting, and a lot of other
> >>>>>>>>> nice features easier.
> >>>>>>>>>
> >>>>>>>>> kunit_config.py:
> >>>>>>>>> - parse .config and Kconfig files.
> >>>>>>>>>
> >>>>>>>>> kunit_kernel.py: provides helper functions to:
> >>>>>>>>> - configure the kernel using kunitconfig.
> >>>>>>>>> - build the kernel with the appropriate configuration.
> >>>>>>>>> - provide function to invoke the kernel and stream the output back.
> >>>>>>>>>
> >>>>>>>>> Signed-off-by: Felix Guo <felixguoxiuping@gmail.com>
> >>>>>>>>> Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
> >>>>>>>>
> >>>>>>>> Ah, here's probably my answer to my previous logging format question,
> >>>>>>>> right? What's the chance that these wrappers output stuff in a standard
> >>>>>>>> format that test-framework-tools can already parse? :)
> >>>>>
> >>>>> To be clear, the test-framework-tools format we are talking about is
> >>>>> TAP13[1], correct?
> >>>>
> >>>> I'm not sure what the test community prefers for a format. I'll let them
> >>>> jump in and debate that question.
> >>>>
> >>>>
> >>>>>
> >>>>> My understanding is that is what kselftest is being converted to use.
> >>>>>
> >>>>>>>
> >>>>>>> It should be pretty easy to do. I had some patches that pack up the
> >>>>>>> results into a serialized format for a presubmit service; it should be
> >>>>>>> pretty straightforward to take the same logic and just change the
> >>>>>>> output format.
> >>>>>>
> >>>>>> When examining and trying out the previous versions of the patch I found
> >>>>>> the wrappers useful to provide information about how to control and use
> >>>>>> the tests, but I had no interest in using the scripts as they do not
> >>>>>> fit in with my personal environment and workflow.
> >>>>>>
> >>>>>> In the previous versions of the patch, these helper scripts are optional,
> >>>>>> which is good for my use case. If the helper scripts are required to
> >>>>>
> >>>>> They are still optional.
> >>>>>
> >>>>>> get the data into the proper format then the scripts are not quite so
> >>>>>> optional, they become the expected environment. I think the proper
> >>>>>> format should exist without the helper scripts.
> >>>>>
> >>>>> That's a good point. A couple things,
> >>>>>
> >>>>> First off, supporting TAP13, either in the kernel or the wrapper
> >>>>> script is not hard, but I don't think that is the real issue that you
> >>>>> raise.
> >>>>>
> >>>>> If your only concern is that you will always be able to have human
> >>>>> readable KUnit results printed to the kernel log, that is a guarantee
> >>>>> I feel comfortable making. Beyond that, I think it is going to take a
> >>>>> long while before I would feel comfortable guaranteeing anything about
> >>>>> how will KUnit work, what kind of data it will want to expose, and how
> >>>>> it will be organized. I think the wrapper script provides a nice
> >>>>> facade that I can maintain, can mediate between the implementation
> >>>>> details and the user, and can mediate between the implementation
> >>>>> details and other pieces of software that might want to consume
> >>>>> results.
> >>>>>
> >>>>> [1] https://testanything.org/tap-version-13-specification.html
> >>>>
> >>>> My concern is based on a focus on my little part of the world
> >>>> (which in _previous_ versions of the patch series was the devicetree
> >>>> unittest.c tests being converted to use the kunit infrastructure).
> >>>> If I step back and think of the entire kernel globally I may end
> >>>> up with a different conclusion - but I'm going to remain myopic
> >>>> for this email.
> >>>>
> >>>> I want the test results to be usable by me and my fellow
> >>>> developers. I prefer that the test results be easily accessible
> >>>> (current printk() implementation means that kunit messages are
> >>>> just as accessible as the current unittest.c printk() output).
> >>>> If the printk() output needs to be filtered through a script
> >>>> to generate the actual test results then that is sub-optimal
> >>>> to me. It is one more step added to my workflow. And
> >>>> potentially with an embedded target a major pain to get a
> >>>> data file (the kernel log file) transferred from a target
> >>>> to my development host.
> >>>
> >>> That's fair. If that is indeed your only concern, then I don't think
> >>> the wrapper script will ever be an issue for you. You will always be
> >>> able to execute a given test the old fashioned/manual way, and the
> >>> wrapper script only summarizes results, it does not change the
> >>> contents.
> >>>
> >>>>
> >>>> I want a reported test failure to be easy to trace back to the
> >>>> point in the source where the failure is reported. With printk()
> >>>> the search is a simple grep for the failure message. If the
> >>>> failure message has been processed by a script, and then the
> >>>> failure reported to me in an email, then I may have to look
> >>>> at the script to reverse engineer how the original failure
> >>>> message was transformed into the message that was reported
> >>>> to me in the email. Then I search for the point in the
> >>>> source where the failure is reported. So a basic task has
> >>>> just become more difficult and time consuming.
> >>>
> >>> That seems to be a valid concern. I would reiterate that you shouldn't
> >>> be concerned by any processing done by the wrapper script itself, but
> >>> the reality is that depending on what happens with automated
> >>> testing/presubmit/CI other people might end up parsing and
> >>> transforming test results - it might happen, it might not.
> >>
> >> You seem to be missing my point.
> >>
> >> Greg asked that the output be in a standard format.
> >>
> >> You replied that the standard format could be created by the wrapper script.
> >
> > I thought Greg originally meant that that is how it could be done when
> > he first commented on this patch, so I was agreeing and elaborating.
> > Nevertheless, it seems you and Greg are now in agreement on this
> > point, so I won't argue it further.
> >
> >>
> >> Now you say that "it might happen, it might not". In other words the output
> >> may or may not end up in the standard format.
> >
> > Sorry, that was in reference to your concern about getting an email in
> > a different format than what the tool that you use generates. It
> > wasn't a statement about what I was or wasn't going to do in regards
> > to supporting a standard format.
> >
> >>
> >> As Greg points out in comments to patch 12:
> >>
> >> "The core of kunit should also log the messages in this format as well,
> >> and not rely on the helper scripts as Frank points out, not everyone
> >> will use/want them. Might as well make it easy for everyone to always
> >> do the right thing and not force it to always be added in later."
> >>
> >> I am requesting that the original message be in the standard format. Of
> >> course anyone is free to transform the messages in later processing, no
> >> big deal.
> >
> > My mistake, I thought that was a concern of yours.
> >
> > In any case, it sounds like you and Greg are in agreement on the core
> > libraries generating the output in TAP13, so I won't argue that point
> > further.
> >
> > ## Analysis of using TAP13
>
> I have never looked at TAP version 13 in any depth at all, so do not consider
> me to be any sort of expert.
>
> My entire TAP knowledge is based on:
>
> https://testanything.org/tap-version-13-specification.html
>
> and the pull request to create the TAP version 14 specification:
>
> https://github.com/TestAnything/testanything.github.io/pull/36/files
>
> You can see the full version 14 document in the submitter's repo:
>
> $ git clone https://github.com/isaacs/testanything.github.io.git
> $ cd testanything.github.io
> $ git checkout tap14
> $ ls tap-version-14-specification.md
>
> My understanding is the the version 14 specification is not trying to
> add new features, but instead capture what is already implemented in
> the wild.
>
>
> > One of my earlier concerns was that TAP13 is a bit over constrained
> > for what I would like to output from the KUnit core. It only allows
> > data to be output as either:
> > - test number
> > - ok/not ok with single line description
> > - directive
> > - diagnostics
> > - YAML block
> >
> > The test number must become before a set of ok/not ok lines, and does
> > not contain any additional information. One annoying thing about this
> > is it doesn't provide any kind of nesting or grouping.
>
> Greg's response mentions ktest (?) already does nesting.

I think we are talking about kselftest.

> Version 14 allows nesting through subtests. I have not looked at what
> ktest does, so I do not know if it uses subtest, or something else.

Oh nice! That is new in version 14. I can use that.

> > There is one ok/not ok line per test and it may have a short
> > description of the test immediately after 'ok' or 'not ok'; this is
> > problematic because it wants the first thing you say about a test to
> > be after you know whether it passes or not.
>
> I think you could output a diagnostic line that says a test is starting.
> This is important to me because printk() errors and warnings that are
> related to a test can be output by a subsystem other than the subsystem
> that I am testing. If there is no marker at the start of the test
> then there is no way to attribute the printk()s to the test.

I agree.

Technically conforms with the spec, and kselftest does that, but is
also not part of the spec. Well, it *is* specified if you use
subtests. I think the right approach is to make each
"kunit_module/test suite" a test, and all the test cases will be
subtests.

> > Directives are just a way to specify skipped tests and TODOs.
> >
> > Diagnostics seem useful, it looks like you can put whatever
> > information in them and print them out at anytime. It looks like a lot
> > of kselftests emit a lot of data this way.
> >
> > The YAML block seems to be the way that they prefer users to emit data
> > beyond number of tests run and whether a test passed or failed. I
> > could express most things I want to express in terms of YAML, but it
> > is not the nicest format for displaying a lot of data like
> > expectations, missed function calls, and other things which have a
> > natural concise representation. Nevertheless, YAML readability is
> > mostly a problem who won't be using the wrapper scripts.
>
> The examples in specification V13 and V14 look very simple and very
> readable to me. (And I am not a fan of YAML.)
>
>
> > My biggest
> > problem with the YAML block is that you can only have one, and TAP
> > specifies that it must come after the corresponding ok/not ok line,
> > which again has the issue that you have to hold on to a lot of
> > diagnostic data longer than you ideally would. Another downside is
> > that I now have to write a YAML serializer for the kernel.
>
> If a test generates diagnostic data, then I would expect that to be
> the direct result of a test failure. So the test can output the
> "not ok" line, then immediately output the YAML block. I do not
> see a need for stashing YAML output ahead of time.
>
> If diagnostic data is generated before the test can determine
> success or failure, then it can be output as diagnostic data
> instead of stashing it for later.

Cool, that's what I am thinking I am going to do - I just wanted to
make sure people were okay with this approach. I mean, I think that is
what kselftest does.

We can hold off on the YAML stuff for now then.

> > ## Here is what I propose for this patchset:
> >
> > - Print out test number range at the beginning of each test suite.
> > - Print out log lines as soon as they happen as diagnostics.
> > - Print out the lines that state whether a test passes or fails as a
> > ok/not ok line.
> >
> > This would be technically conforming with TAP13 and is consistent with
> > what some kselftests have done.
> >
> > ## To be done in a future patchset:
> >
> > Add a YAML serializer and print out some logs containing structured
> > data (like expectation failures, unexpected function calls, etc) in
> > YAML blocks.
>
> YAML serializer sounds like not needed complexity.
>
> >
> > Does this sound reasonable? I will go ahead and start working on this,
> > but feel free to give me feedback on the overall idea in the meantime.
> >
> > Cheers

Thanks!