On Thu, 27 Aug 2020 at 18:17, David Gow <davidgow@xxxxxxxxxx> wrote: [...] > > First of all, thanks for the talk yesterday! I only looked at this > > because somebody pasted the LKML link. :-) > > No worries! Clearly this document needed linking -- even I was > starting to suspect the reason no-one was complaining about this was > that no-one had read it. :-) [...] > > > > While I guess this ship has sailed, and *_kunit.c is the naming > > convention now, I hope this is still just a recommendation and names of > > the form *-test.c are not banned! > > The ship hasn't technically sailed until this patch is actually > accepted. Thus far, we hadn't had any real complaints about the > _kunit.c idea, though that may have been due to this email not > reaching enough people. If you haven't read the discussion in > https://lore.kernel.org/linux-kselftest/202006141005.BA19A9D3@keescook/t/#u > it's worthwhile: the _kunit.c name is discussed, and Kees lays out > some more detailed rationale for it as well. Thanks, I can see the rationale. AFAIK the main concern was "it does not distinguish it from other tests". > > $> git grep 'KUNIT.*-test.o' > > drivers/base/power/Makefile:obj-$(CONFIG_PM_QOS_KUNIT_TEST) += qos-test.o > > drivers/base/test/Makefile:obj-$(CONFIG_KUNIT_DRIVER_PE_TEST) += property-entry-test.o > > fs/ext4/Makefile:obj-$(CONFIG_EXT4_KUNIT_TESTS) += ext4-inode-test.o > > kernel/Makefile:obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o > > lib/Makefile:obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o > > lib/kunit/Makefile:obj-$(CONFIG_KUNIT_TEST) += kunit-test.o > > lib/kunit/Makefile:obj-$(CONFIG_KUNIT_TEST) += string-stream-test.o > > lib/kunit/Makefile:obj-$(CONFIG_KUNIT_EXAMPLE_TEST) += kunit-example-test.o > > > > $> git grep 'KUNIT.*_kunit.o' > > # Returns nothing > > > > This was definitely something we noted. Part of the goal of having > _kunit.c as a filename suffix (and, perhaps more importantly, the > _kunit module name suffix) was to have a way of both distinguishing > KUnit tests from non-KUnit ones (of which there are quite a few > already with -test names), and to have a way of quickly determining > what modules contain KUnit tests. That really only works if everyone > is using it, so the plan was to push this as much as possible. This'd > probably include renaming most of the existing test files to match, > which is a bit of a pain (particularly when converting non-KUnit tests > to KUnit and similar), but is a one-time thing. Feel free to ignore the below, but here might be one concern: I think the problem of distinguishing KUnit tests from non-KUnit tests is a technical problem (in fact, the Kconfig entries have all the info we need), but a solution that sacrifices readability might cause unnecessary friction. The main issue I foresee is that the _kunit.c name is opaque as to what the file does, but merely indicates one of its dependencies. Most of us clearly know that KUnit is a test framework, but it's a level of indirection nevertheless. (But _kunit_test.c is also bad, because it's unnecessarily long.) For a dozen tests, that's probably still fine. But now imagine 100s of tests, people will quickly wonder "what's this _kunit thing?". And if KUnit tests are eventually the dominant tests, does it still matter? I worry that because of the difficulty of enforcing the name, choosing something unintuitive will also achieve the opposite result: proliferation of even more diverse names. A generic convention like "*-test.c" will be close enough to what's intuitive for most people, and we might actually have a chance of getting everyone to stick to it. The problem of identifying all KUnit tests can be solved with a script. > > Just an idea: Maybe the names are also an opportunity to distinguish > > real _unit_ style tests and then the rarer integration-style tests. I > > personally prefer using the more generic *-test.c, at least for the > > integration-style tests I've been working on (KUnit is still incredibly > > valuable for integration-style tests, because otherwise I'd have to roll > > my own poor-man's version of KUnit, so thank you!). Using *_kunit.c for > > such tests is unintuitive, because the word "unit" hints at "unit tests" > > -- and having descriptive (and not misleading) filenames is still > > important. So I hope you won't mind if *-test.c are still used where > > appropriate. > > As Brendan alluded to in the talk, the popularity of KUnit for these > integration-style tests came as something of a surprise (more due to > our lack of imagination than anything else, I suspect). It's great > that it's working, though: I don't think anyone wants the world filled > with more single-use test "frameworks" than is necessary! > > I guess the interesting thing to note is that we've to date not really > made a distinction between KUnit the framework and the suite of all > KUnit tests. Maybe having a separate file/module naming scheme could > be a way of making that distinction, though it'd really only appear > when loading tests as modules -- there'd be no indication in e.g., > suite names or test results. The more obvious solution to me (at > least, based on the current proposal) would be to have "integration" > or similar be part of the suite name (and hence the filename, so > _integration_kunit.c or similar), though even I admit that that's much > uglier. Yeah, that's not great either. Again, in the end it's probably entirely up to you, but it'd be good if the filenames are descriptive and readable (vs. a puzzle). > Maybe the idea of having the subsystem/suite distinction be > represented in the code could pave the way to having different suites > support different suffixes like that. > Do you know of any cases where something has/would have both > unit-style tests and integration-style tests built with KUnit where > the distinction needs to be clear? None I know of, so probably not a big deal. > Brendan, Kees: do you have any thoughts? > > Cheers, > -- David Thanks, -- Marco
