linux-kernel - Re: [PATCH v1 0/2] kunit: add macro to allow conditionally exposing static symbols to tests

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Date:   Mon, 21 Nov 2022 22:13:19 -0800
From:   John Johansen <john.johansen@...onical.com>
To:     Rae Moar <rmoar@...gle.com>, brendanhiggins@...gle.com,
        davidgow@...gle.com, dlatypov@...gle.com
Cc:     skhan@...uxfoundation.org, tales.aparecida@...il.com,
        kunit-dev@...glegroups.com, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, apparmor@...ts.ubuntu.com
Subject: Re: [PATCH v1 0/2] kunit: add macro to allow conditionally exposing
 static symbols to tests

sorry for the delay on this

On 11/2/22 10:59, Rae Moar wrote:
> Currently in order to test a static function, tests must be included in the
> same translation unit as the function. However, this can cause issues with
> including implementation and test code in the same file. As an alternative,

And the issue is? An ugly include of C file that only happens if kunit is
built. Also that you can't make the kunit code a module but is that really
an issue?
  
> the first patch in this series creates a macro that will set a function to
> be static or not depending on whether CONFIG_KUNIT is enabled. This allows
> the function to be visible during testing and static otherwise.
> 
> As an example, the current status quo to test static functions is:
> 
> === test.c ===
> 
> static void test_case(struct kunit *test)
> {
>    KUNIT_EXPECT_EQ(test, my_func_to_test(), 2);
> }
> 
> Then the tests are included in the implementation file as a workaround to
> the issue of testing static functions:
> 
> === implementation.c ===
> 
> static int my_func_to_test() {...}
> ...
> #include "test.c"
> 
> Instead, the function could be defined with this new macro:
> 
> === implementation.c ===
> 
> VISIBLE_IF_KUNIT int my_func_to_test() {...}
> 
> The first patch also creates a macro that will export a symbol into a kunit
> testing namespace only if CONFIG_KUNIT is enabled. This follows the logic
> above and allows symbols to be conditionally exported based on the testing
> status.
> 
> The second patch in the series updates the policy_unpack test in AppArmor
> to show an example of how to use both of these macros in order to address
> the issue of testing static functions.
> 
> Rae Moar (2):
>    kunit: add macro to allow conditionally exposing static symbols to
>      tests
>    apparmor: test: make static symbols visible during kunit testing
> 
>   include/kunit/visibility.h                | 32 ++++++++++
>   security/apparmor/Kconfig                 |  4 +-
>   security/apparmor/Makefile                |  2 +
>   security/apparmor/include/policy_unpack.h | 50 ++++++++++++++++
>   security/apparmor/policy_unpack.c         | 72 +++++++----------------
>   security/apparmor/policy_unpack_test.c    |  5 ++
>   6 files changed, 112 insertions(+), 53 deletions(-)
>   create mode 100644 include/kunit/visibility.h
> 
> 
> base-commit: 11e76194937b506caf1b49512c42d5c2588681d7