Re: [PATCH v2 2/2] drm/tests: Change "igt_" prefix to "test_drm_"

[Maíra Canal]

On 9/5/22 09:10, Maxime Ripard wrote:
> On Fri, Sep 02, 2022 at 03:38:28PM +0200, Michał Winiarski wrote:
>> On Fri, Sep 02, 2022 at 04:03:20PM +0300, Jani Nikula wrote:
>>> On Fri, 02 Sep 2022, Maxime Ripard <maxime@xxxxxxxxxx> wrote:
>>>> On Fri, Sep 02, 2022 at 11:04:14AM +0300, Jani Nikula wrote:
>>>>> On Thu, 01 Sep 2022, Maíra Canal <mairacanal@xxxxxxxxxx> wrote:
>>>>>> Hi Maxime,
>>>>>>
>>>>>> On 9/1/22 09:55, Maxime Ripard wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> On Thu, Sep 01, 2022 at 09:42:10AM -0300, Maíra Canal wrote:
>>>>>>>> With the introduction of KUnit, IGT is no longer the only option to run
>>>>>>>> the DRM unit tests, as the tests can be run through kunit-tool or on
>>>>>>>> real hardware with CONFIG_KUNIT.
>>>>>>>>
>>>>>>>> Therefore, remove the "igt_" prefix from the tests and replace it with
>>>>>>>> the "test_drm_" prefix, making the tests' names independent from the tool
>>>>>>>> used.
>>>>>>>>
>>>>>>>> Signed-off-by: Maíra Canal <mairacanal@xxxxxxxxxx>
>>>>>>>>
>>>>>>>> ---
>>>>>>>> v1 -> v2: https://lore.kernel.org/dri-devel/20220830211603.191734-1-mairacanal@xxxxxxxxxx/
>>>>>>>> - Change "drm_" prefix to "test_drm_", as "drm_" can be a bit confusing (Jani Nikula).
>>>>>>>
>>>>>>> I appreciate it's a bit of a bikeshed but I disagree with this. The
>>>>>>> majority of the kunit tests already out there start with the framework
>>>>>>> name, including *all* the examples in the kunit doc. Plus, it's fairly
>>>>>>> obvious that it's a test, kunit is only about running tests in the first
>>>>>>> place.
>>>>>>
>>>>>> Would it be better to keep it as "drm_"?
>>>>>
>>>>> That's not "keeping". That's renaming igt to drm.
>>>>
>>>> Well, there's like half the tests that are prefixed with drm, the other
>>>> with igt, so it's both really
>>>>
>>>>>> Currently, I don't think it is appropriate to hold the "igt_" prefix, as
>>>>>> the tests are not IGT exclusive, but I don't have a strong opinion on
>>>>>> using the "drm_" or the "test_drm" prefixes.
>>>>>
>>>>> I repeat my stance that "drm_" alone is confusing.
>>>>
>>>> What are you confusing it with?
>>>>
>>>>> For the reason alone that it pollutes the code tagging tools, mixing
>>>>> actual drm_ types and functions with unit test functions.
>>>>
>>>> I don't get it, I'm sorry. All these functions are static and not part
>>>> of any API, so I can't see how it would pollute a code tagging tool. Or
>>>> at least, not more than any driver does.
>>>>
>>>> And we're part of a larger project here, it's about consistency with the
>>>> rest of the ecosystem.
>>>
>>> Okay, so I'm just going to explain what I mean, but say "whatever" right
>>> after and move on.
>>>
>>> For example, drm_buddy_test.c includes drm_buddy.h so with the igt_ ->
>>> drm_ rename none of the test functions may clash with the drm_buddy_
>>> prefixed existing functions. Ditto for all tests similarly.
>>>
>>> For example drm_buddy_alloc_range() as a name sounds like something that
>>> allocs a range, not something that tests range allocation. On the other
>>> hand, you have drm_buddy_alloc_blocks() which is actually a real
>>> drm_buddy function, not a test. What would you call a test that tests
>>> that? Here, we end up with names that are all prefixed drm_buddy and you
>>> won't know what's the actual function and what's the test unless you
>>> look it up.
>>>
>>> I use code tagging that I can use for finding and completing
>>> e.g. functions. Currently I have the following completions, for
>>> igt_buddy_ and drm_buddy_, respectively:
>>>
>>> Possible completions are:
>>> igt_buddy_alloc_limit 	igt_buddy_alloc_optimistic 	igt_buddy_alloc_pathological
>>> igt_buddy_alloc_pessimistic 	igt_buddy_alloc_range 	igt_buddy_alloc_smoke
>>>
>>> Possible completions are:
>>> drm_buddy_alloc_blocks 	drm_buddy_block 	drm_buddy_block_is_allocated 	drm_buddy_block_is_free
>>> drm_buddy_block_is_split 	drm_buddy_block_offset 	drm_buddy_block_order 	drm_buddy_block_print
>>> drm_buddy_block_size 	drm_buddy_block_state 	drm_buddy_block_trim 	drm_buddy_fini
>>> drm_buddy_free_block 	drm_buddy_free_list 	drm_buddy_init 	drm_buddy_init_test
>>> drm_buddy_module_exit 	drm_buddy_module_init 	drm_buddy_print
>>>
>>> With the patch at hand, they'll all be lumped under drm_buddy_
>>> completions, and some of them will be actual drm buddy functions and
>>> some not.
>>>
>>> I just find it a very odd convention to name the tests in a way that's
>>> indistinguishable from the real things. Even *within* drm_buddy_test.c
>>> where you read the test code. Because currently you do have calls to
>>> igt_buddy_ prefixed functions from other igt_buddy_ prefixed functions,
>>> along with the drm_buddy_ prefixed calls. I think it's just going to be
>>> a mess.
>>>
>>> /rant
>>>
>>> Whatever. Moving on.
>>
>> KUnit docs [1] state:
>> https://docs.kernel.org/dev-tools/kunit/style.html#test-cases
>> "As tests are themselves functions, their names cannot conflict with other
>> C identifiers in the kernel. This may require some creative naming."
>> And give examples of names. But this should be local to individual test suite -
>> as long as the test is readable, and the name describes what it is testing, we
>> should be fine. We don't even need to pass drm_* prefix, as this convention is
>> expected for test suites, not test cases [2].
>>
>> Having said that - I do believe that igt_* prefix don't belong here (which is
>> why I'm progressively trying to get rid of in the patches that refactor some of
>> the tests).
>> I agree with Jani - can we take it on a case-by-case basis?
>> If the test name is too similar to the function that it is testing, we could go
>> with one of the following (taking igt_buddy_alloc_limit as example):
>> drm_buddy_test_alloc_limit
>> test_drm_buddy_alloc_limit
>> buddy_test_alloc_limit
>> test_buddy_alloc_limit
> 
> We also have drm_test_buddy_alloc_limit, or drm_buddy_test_alloc_limit

I will send a v3 with the "drm_test" prefix, as it seems we can get a
bit more consensus with this one.

Best Regards,
- Maíra Canal

> 
> Both would be fine for me, with a small preference for the former, which
> should also address Jani's concerns?
> 
>> And either of those is fine in my opinion (I'd personally go with
>> test_buddy_alloc_limit in this case).
>> We don't really need a DRM-wide (or worse, kernel wide) convention for test case
>> names (it's only really needed for test suites).
> 
> Sure we do. kunit.py can take some filters too. Being able to only run
> DRM tests with a single filter is super convenient, and if we fail to
> provide a consistent naming we're pretty much sure people running the
> tests are going to miss some.
> 
> Maxime