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    SubjectRe: [PATCH v2 00/17] kunit: introduce KUnit, the Linux kernel unit testing framework
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    On Thu, 2019-05-09 at 22:18 -0700, Frank Rowand wrote:
    > On 5/9/19 4:40 PM, Logan Gunthorpe wrote:
    > >
    > >
    > > On 2019-05-09 5:30 p.m., Theodore Ts'o wrote:
    > >> On Thu, May 09, 2019 at 04:20:05PM -0600, Logan Gunthorpe wrote:
    > >>>
    > >>> The second item, arguably, does have significant overlap with kselftest.
    > >>> Whether you are running short tests in a light weight UML environment or
    > >>> higher level tests in an heavier VM the two could be using the same
    > >>> framework for writing or defining in-kernel tests. It *may* also be valuable
    > >>> for some people to be able to run all the UML tests in the heavy VM
    > >>> environment along side other higher level tests.
    > >>>
    > >>> Looking at the selftests tree in the repo, we already have similar items to
    > >>> what Kunit is adding as I described in point (2) above. kselftest_harness.h
    > >>> contains macros like EXPECT_* and ASSERT_* with very similar intentions to
    > >>> the new KUNIT_EXECPT_* and KUNIT_ASSERT_* macros.
    > >>>
    > >>> However, the number of users of this harness appears to be quite small. Most
    > >>> of the code in the selftests tree seems to be a random mismash of scripts
    > >>> and userspace code so it's not hard to see it as something completely
    > >>> different from the new Kunit:
    > >>>
    > >>> $ git grep --files-with-matches kselftest_harness.h *
    > >>
    > >> To the extent that we can unify how tests are written, I agree that
    > >> this would be a good thing. However, you should note that
    > >> kselftest_harness.h is currently assums that it will be included in
    > >> userspace programs. This is most obviously seen if you look closely
    > >> at the functions defined in the header files which makes calls to
    > >> fork(), abort() and fprintf().
    > >
    > > Ah, yes. I obviously did not dig deep enough. Using kunit for
    > > in-kernel tests and kselftest_harness for userspace tests seems like
    > > a sensible line to draw to me. Trying to unify kernel and userspace
    > > here sounds like it could be difficult so it's probably not worth
    > > forcing the issue unless someone wants to do some really fancy work
    > > to get it done.
    > >
    > > Based on some of the other commenters, I was under the impression
    > > that kselftests had in-kernel tests but I'm not sure where or if they
    > > exist.
    >
    > YES, kselftest has in-kernel tests. (Excuse the shouting...)
    >
    > Here is a likely list of them in the kernel source tree:
    >
    > $ grep module_init lib/test_*.c
    > lib/test_bitfield.c:module_init(test_bitfields)
    > lib/test_bitmap.c:module_init(test_bitmap_init);
    > lib/test_bpf.c:module_init(test_bpf_init);
    > lib/test_debug_virtual.c:module_init(test_debug_virtual_init);
    > lib/test_firmware.c:module_init(test_firmware_init);
    > lib/test_hash.c:module_init(test_hash_init); /* Does everything */
    > lib/test_hexdump.c:module_init(test_hexdump_init);
    > lib/test_ida.c:module_init(ida_checks);
    > lib/test_kasan.c:module_init(kmalloc_tests_init);
    > lib/test_list_sort.c:module_init(list_sort_test);
    > lib/test_memcat_p.c:module_init(test_memcat_p_init);
    > lib/test_module.c:static int __init test_module_init(void)
    > lib/test_module.c:module_init(test_module_init);
    > lib/test_objagg.c:module_init(test_objagg_init);
    > lib/test_overflow.c:static int __init test_module_init(void)
    > lib/test_overflow.c:module_init(test_module_init);
    > lib/test_parman.c:module_init(test_parman_init);
    > lib/test_printf.c:module_init(test_printf_init);
    > lib/test_rhashtable.c:module_init(test_rht_init);
    > lib/test_siphash.c:module_init(siphash_test_init);
    > lib/test_sort.c:module_init(test_sort_init);
    > lib/test_stackinit.c:module_init(test_stackinit_init);
    > lib/test_static_key_base.c:module_init(test_static_key_base_init);
    > lib/test_static_keys.c:module_init(test_static_key_init);
    > lib/test_string.c:module_init(string_selftest_init);
    > lib/test_ubsan.c:module_init(test_ubsan_init);
    > lib/test_user_copy.c:module_init(test_user_copy_init);
    > lib/test_uuid.c:module_init(test_uuid_init);
    > lib/test_vmalloc.c:module_init(vmalloc_test_init)
    > lib/test_xarray.c:module_init(xarray_checks);
    >
    >
    > > If they do exists, it seems like it would make sense to
    > > convert those to kunit and have Kunit tests run-able in a VM or
    > > baremetal instance.
    >
    > They already run in a VM.
    >
    > They already run on bare metal.
    >
    > They already run in UML.
    >
    > This is not to say that KUnit does not make sense. But I'm still trying
    > to get a better description of the KUnit features (and there are
    > some).

    FYI, I have a master student who looks at converting some of these to KTF, such as for
    instance the XArray tests, which lended themselves quite good to a semi-automated
    conversion.

    The result is also a somewhat more compact code as well as the flexibility
    provided by the Googletest executor and the KTF frameworks, such as running selected
    tests, output formatting, debugging features etc.

    Knut

    > -Frank

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