[PATCH v2] Documentation: KUnit: Update filename best practices

[Kees Cook <kees@kernel.org>]

Based on feedback from Linus[1] and follow-up discussions, change the
suggested file naming for KUnit tests.

Link: https://lore.kernel.org/lkml/CAHk-=wgim6pNiGTBMhP8Kd3tsB7_JTAuvNJ=XYd3wPvvk=OHog@mail.gmail.com/ [1]
Signed-off-by: Kees Cook <kees@kernel.org>
---
Cc: David Gow <davidgow@google.com>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: Rae Moar <rmoar@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kselftest@vger.kernel.org
Cc: kunit-dev@googlegroups.com
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-hardening@vger.kernel.org
---
 Documentation/dev-tools/kunit/style.rst | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/Documentation/dev-tools/kunit/style.rst b/Documentation/dev-tools/kunit/style.rst
index b6d0d7359f00..1538835cd0e2 100644
--- a/Documentation/dev-tools/kunit/style.rst
+++ b/Documentation/dev-tools/kunit/style.rst
@@ -188,15 +188,20 @@ For example, a Kconfig entry might look like:
 Test File and Module Names
 ==========================
 
-KUnit tests can often be compiled as a module. These modules should be named
-after the test suite, followed by ``_test``. If this is likely to conflict with
-non-KUnit tests, the suffix ``_kunit`` can also be used.
-
-The easiest way of achieving this is to name the file containing the test suite
-``<suite>_test.c`` (or, as above, ``<suite>_kunit.c``). This file should be
-placed next to the code under test.
+Whether a KUnit test is compiled as a separate module or via an
+``#include`` in a core kernel source file, the file should be named
+after the test suite, followed by ``_kunit``, and live in a ``tests``
+subdirectory to avoid conflicting with regular modules (e.g. if "foobar"
+is the core module, then "foobar_kunit" is the KUnit test module) or the
+core kernel source file names (e.g. for tab-completion). Many existing
+tests use a ``_test`` suffix, but this is considered deprecated.
+
+So for the common case, name the file containing the test suite
+``tests/<suite>_kunit.c``. The ``tests`` directory should be placed at
+the same level as the code under test. For example, tests for
+``lib/string.c`` live in ``lib/tests/string_kunit.c``.
 
 If the suite name contains some or all of the name of the test's parent
-directory, it may make sense to modify the source filename to reduce redundancy.
-For example, a ``foo_firmware`` suite could be in the ``foo/firmware_test.c``
-file.
+directory, it may make sense to modify the source filename to reduce
+redundancy. For example, a ``foo_firmware`` suite could be in the
+``tests/foo/firmware_kunit.c`` file.
-- 
2.34.1