As discussed in [1], KUnit tests have hitherto not had a particularly
consistent naming scheme. This adds documentation outlining how tests
and test suites should be named, including how those names should be
used in Kconfig entries and filenames.
[1]:
https://lore.kernel.org/linux-kselftest/202006141005.BA19A9D3@keescook/t/#u
Signed-off-by: David Gow <davidgow(a)google.com>
Reviewed-by: Kees Cook <keescook(a)chromium.org>
Reviewed-by: Brendan Higgins <brendanhiggins(a)google.com>
---
This is v2 of the KUnit test nomenclature guidelines. The guidelines have
changed a bit in response to the discussion on the v1 thread which came
about after plumbers. The major change is that the filename suffix is
now "_test", with "_kunit" permitted where it conflicts. There are also
some other exceptions carved out around existing tests, and very
non-unit-like tests.
Changelog:
v2:
- Rewrote the filename section to use "_test" as a suffix, and focus on
module names, not filenames.
- Add a motivating introduction, which also calls out existing tests and
tests which cause problems when run automatically (long running,
flaky tests) as reasons to avoid the guidelines.
- Talk about including the type of test in the suite name, but only if
theres an actual confict. (And update the example for this).
v1:
https://lore.kernel.org/linux-kselftest/20200702071416.1780522-1-davidgow@g…
- Fixed a bit of space/tab confusion in the index (Thanks, Randy)
- Added some more examples (and some test case examples).
- Added some examples of what not to call subsystems and suites.
- No longer explicitly require "If unsure, put N" in Kconfig entries.
- Minor formatting changes
RFC:
https://lore.kernel.org/linux-kselftest/20200620054944.167330-1-davidgow@go…
- Initial version
The result is a little bit weaker than the previous versions, but
hopefully will let us get the areas we agree on down.
-- David
Documentation/dev-tools/kunit/index.rst | 1 +
Documentation/dev-tools/kunit/style.rst | 207 ++++++++++++++++++++++++
2 files changed, 208 insertions(+)
create mode 100644 Documentation/dev-tools/kunit/style.rst
diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst
index e93606ecfb01..c234a3ab3c34 100644
--- a/Documentation/dev-tools/kunit/index.rst
+++ b/Documentation/dev-tools/kunit/index.rst
@@ -11,6 +11,7 @@ KUnit - Unit Testing for the Linux Kernel
usage
kunit-tool
api/index
+ style
faq
What is KUnit?
diff --git a/Documentation/dev-tools/kunit/style.rst b/Documentation/dev-tools/kunit/style.rst
new file mode 100644
index 000000000000..c001ea1cd87d
--- /dev/null
+++ b/Documentation/dev-tools/kunit/style.rst
@@ -0,0 +1,207 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
+Test Style and Nomenclature
+===========================
+
+To make finding, writing, and using KUnit tests as simple as possible, it's
+strongly encouraged that they are named and written according to the guidelines
+below. While it's possible to write KUnit tests which do not follow these rules,
+they may break some tooling, may conflict with other tests, and may not be run
+automatically by testing systems.
+
+It's recommended that you only deviate from these guidelines when:
+
+1. Porting tests to KUnit which are already known with an existing name, or
+2. Writing tests which would cause serious problems if automatically run (e.g.,
+ nonderministically producing false positives or negatives, or taking an
+ extremely long time to run).
+
+Subsystems, Suites, and Tests
+=============================
+
+In order to make tests as easy to find as possible, they're grouped into suites
+and subsystems. A test suite is a group of tests which test a related area of
+the kernel, and a subsystem is a set of test suites which test different parts
+of the same kernel subsystem or driver.
+
+Subsystems
+----------
+
+Every test suite must belong to a subsystem. A subsystem is a collection of one
+or more KUnit test suites which test the same driver or part of the kernel. A
+rule of thumb is that a test subsystem should match a single kernel module. If
+the code being tested can't be compiled as a module, in many cases the subsystem
+should correspond to a directory in the source tree or an entry in the
+MAINTAINERS file. If unsure, follow the conventions set by tests in similar
+areas.
+
+Test subsystems should be named after the code being tested, either after the
+module (wherever possible), or after the directory or files being tested. Test
+subsystems should be named to avoid ambiguity where necessary.
+
+If a test subsystem name has multiple components, they should be separated by
+underscores. *Do not* include "test" or "kunit" directly in the subsystem name
+unless you are actually testing other tests or the kunit framework itself.
+
+Example subsystems could be:
+
+``ext4``
+ Matches the module and filesystem name.
+``apparmor``
+ Matches the module name and LSM name.
+``kasan``
+ Common name for the tool, prominent part of the path ``mm/kasan``
+``snd_hda_codec_hdmi``
+ Has several components (``snd``, ``hda``, ``codec``, ``hdmi``) separated by
+ underscores. Matches the module name.
+
+Avoid names like these:
+
+``linear-ranges``
+ Names should use underscores, not dashes, to separate words. Prefer
+ ``linear_ranges``.
+``qos-kunit-test``
+ As well as using underscores, this name should not have "kunit-test" as a
+ suffix, and ``qos`` is ambiguous as a subsystem name. ``power_qos`` would be a
+ better name.
+``pc_parallel_port``
+ The corresponding module name is ``parport_pc``, so this subsystem should also
+ be named ``parport_pc``.
+
+.. note::
+ The KUnit API and tools do not explicitly know about subsystems. They're
+ simply a way of categorising test suites and naming modules which
+ provides a simple, consistent way for humans to find and run tests. This
+ may change in the future, though.
+
+Suites
+------
+
+KUnit tests are grouped into test suites, which cover a specific area of
+functionality being tested. Test suites can have shared initialisation and
+shutdown code which is run for all tests in the suite.
+Not all subsystems will need to be split into multiple test suites (e.g. simple drivers).
+
+Test suites are named after the subsystem they are part of. If a subsystem
+contains several suites, the specific area under test should be appended to the
+subsystem name, separated by an underscore.
+
+In the event that there are multiple types of test using KUnit within a
+subsystem (e.g., both unit tests and integration tests), they should be put into
+separate suites, with the type of test as the last element in the suite name.
+Unless these tests are actually present, avoid using ``_test``, ``_unittest`` or
+similar in the suite name.
+
+The full test suite name (including the subsystem name) should be specified as
+the ``.name`` member of the ``kunit_suite`` struct, and forms the base for the
+module name (see below).
+
+Example test suites could include:
+
+``ext4_inode``
+ Part of the ``ext4`` subsystem, testing the ``inode`` area.
+``kunit_try_catch``
+ Part of the ``kunit`` implementation itself, testing the ``try_catch`` area.
+``apparmor_property_entry``
+ Part of the ``apparmor`` subsystem, testing the ``property_entry`` area.
+``kasan``
+ The ``kasan`` subsystem has only one suite, so the suite name is the same as
+ the subsystem name.
+
+Avoid names like:
+
+``ext4_ext4_inode``
+ There's no reason to state the subsystem twice.
+``property_entry``
+ The suite name is ambiguous without the subsystem name.
+``kasan_integration_test``
+ Because there is only one suite in the ``kasan`` subsystem, the suite should
+ just be called ``kasan``. There's no need to redundantly add
+ ``integration_test``. Should a separate test suite with, for example, unit
+ tests be added, then that suite could be named ``kasan_unittest`` or similar.
+
+Test Cases
+----------
+
+Individual tests consist of a single function which tests a constrained
+codepath, property, or function. In the test output, individual tests' results
+will show up as subtests of the suite's results.
+
+Tests should be named after what they're testing. This is often the name of the
+function being tested, with a description of the input or codepath being tested.
+As tests are C functions, they should be named and written in accordance with
+the kernel coding style.
+
+.. note::
+ As tests are themselves functions, their names cannot conflict with
+ other C identifiers in the kernel. This may require some creative
+ naming. It's a good idea to make your test functions `static` to avoid
+ polluting the global namespace.
+
+Example test names include:
+
+``unpack_u32_with_null_name``
+ Tests the ``unpack_u32`` function when a NULL name is passed in.
+``test_list_splice``
+ Tests the ``list_splice`` macro. It has the prefix ``test_`` to avoid a
+ name conflict with the macro itself.
+
+
+Should it be necessary to refer to a test outside the context of its test suite,
+the *fully-qualified* name of a test should be the suite name followed by the
+test name, separated by a colon (i.e. ``suite:test``).
+
+Test Kconfig Entries
+====================
+
+Every test suite should be tied to a Kconfig entry.
+
+This Kconfig entry must:
+
+* be named ``CONFIG_<name>_KUNIT_TEST``: where <name> is the name of the test
+ suite.
+* be listed either alongside the config entries for the driver/subsystem being
+ tested, or be under [Kernel Hacking]→[Kernel Testing and Coverage]
+* depend on ``CONFIG_KUNIT``
+* be visible only if ``CONFIG_KUNIT_ALL_TESTS`` is not enabled.
+* have a default value of ``CONFIG_KUNIT_ALL_TESTS``.
+* have a brief description of KUnit in the help text
+
+Unless there's a specific reason not to (e.g. the test is unable to be built as
+a module), Kconfig entries for tests should be tristate.
+
+An example Kconfig entry:
+
+.. code-block:: none
+
+ config FOO_KUNIT_TEST
+ tristate "KUnit test for foo" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ This builds unit tests for foo.
+
+ For more information on KUnit and unit tests in general, please refer
+ to the KUnit documentation in Documentation/dev-tools/kunit
+
+ If unsure, say N
+
+
+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 suffic ``_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.
+
+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.
+
+
--
2.28.0.526.ge36021eeef-goog
From: Mattias Nissler <mnissler(a)chromium.org>
For mounts that have the new "nosymfollow" option, don't follow symlinks
when resolving paths. The new option is similar in spirit to the
existing "nodev", "noexec", and "nosuid" options, as well as to the
LOOKUP_NO_SYMLINKS resolve flag in the openat2(2) syscall. Various BSD
variants have been supporting the "nosymfollow" mount option for a long
time with equivalent implementations.
Note that symlinks may still be created on file systems mounted with
the "nosymfollow" option present. readlink() remains functional, so
user space code that is aware of symlinks can still choose to follow
them explicitly.
Setting the "nosymfollow" mount option helps prevent privileged
writers from modifying files unintentionally in case there is an
unexpected link along the accessed path. The "nosymfollow" option is
thus useful as a defensive measure for systems that need to deal with
untrusted file systems in privileged contexts.
More information on the history and motivation for this patch can be
found here:
https://sites.google.com/a/chromium.org/dev/chromium-os/chromiumos-design-d…
Signed-off-by: Mattias Nissler <mnissler(a)chromium.org>
Signed-off-by: Ross Zwisler <zwisler(a)google.com>
Reviewed-by: Aleksa Sarai <cyphar(a)cyphar.com>
---
Changes since v8 [1]:
* Look for MNT_NOSYMFOLLOW in link->mnt->mnt_flags so we are testing
the link itself rather than the directory holding the link. (Al Viro)
* Rebased onto v5.9-rc2.
After this lands I will upstream changes to util-linux[2] and man-pages
[3].
[1]: https://patchwork.kernel.org/patch/11724607/
[2]: https://github.com/rzwisler/util-linux/commit/7f8771acd85edb70d97921c026c55…
[3]: https://github.com/rzwisler/man-pages/commit/b8fe8079f64b5068940c0144586e58…
---
fs/namei.c | 3 ++-
fs/namespace.c | 2 ++
fs/proc_namespace.c | 1 +
fs/statfs.c | 2 ++
include/linux/mount.h | 3 ++-
include/linux/statfs.h | 1 +
include/uapi/linux/mount.h | 1 +
7 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index e99e2a9da0f7d..33e8c79bc761e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1626,7 +1626,8 @@ static const char *pick_link(struct nameidata *nd, struct path *link,
return ERR_PTR(error);
}
- if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS))
+ if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS) ||
+ unlikely(link->mnt->mnt_flags & MNT_NOSYMFOLLOW))
return ERR_PTR(-ELOOP);
if (!(nd->flags & LOOKUP_RCU)) {
diff --git a/fs/namespace.c b/fs/namespace.c
index bae0e95b3713a..6408788a649e1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3160,6 +3160,8 @@ int path_mount(const char *dev_name, struct path *path,
mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
if (flags & MS_RDONLY)
mnt_flags |= MNT_READONLY;
+ if (flags & MS_NOSYMFOLLOW)
+ mnt_flags |= MNT_NOSYMFOLLOW;
/* The default atime for remount is preservation */
if ((flags & MS_REMOUNT) &&
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 3059a9394c2d6..e59d4bb3a89e4 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -70,6 +70,7 @@ static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
{ MNT_NOATIME, ",noatime" },
{ MNT_NODIRATIME, ",nodiratime" },
{ MNT_RELATIME, ",relatime" },
+ { MNT_NOSYMFOLLOW, ",nosymfollow" },
{ 0, NULL }
};
const struct proc_fs_opts *fs_infop;
diff --git a/fs/statfs.c b/fs/statfs.c
index 2616424012ea7..59f33752c1311 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -29,6 +29,8 @@ static int flags_by_mnt(int mnt_flags)
flags |= ST_NODIRATIME;
if (mnt_flags & MNT_RELATIME)
flags |= ST_RELATIME;
+ if (mnt_flags & MNT_NOSYMFOLLOW)
+ flags |= ST_NOSYMFOLLOW;
return flags;
}
diff --git a/include/linux/mount.h b/include/linux/mount.h
index de657bd211fa6..aaf343b38671c 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -30,6 +30,7 @@ struct fs_context;
#define MNT_NODIRATIME 0x10
#define MNT_RELATIME 0x20
#define MNT_READONLY 0x40 /* does the user want this to be r/o? */
+#define MNT_NOSYMFOLLOW 0x80
#define MNT_SHRINKABLE 0x100
#define MNT_WRITE_HOLD 0x200
@@ -46,7 +47,7 @@ struct fs_context;
#define MNT_SHARED_MASK (MNT_UNBINDABLE)
#define MNT_USER_SETTABLE_MASK (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
| MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
- | MNT_READONLY)
+ | MNT_READONLY | MNT_NOSYMFOLLOW)
#define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
diff --git a/include/linux/statfs.h b/include/linux/statfs.h
index 9bc69edb8f188..fac4356ea1bfc 100644
--- a/include/linux/statfs.h
+++ b/include/linux/statfs.h
@@ -40,6 +40,7 @@ struct kstatfs {
#define ST_NOATIME 0x0400 /* do not update access times */
#define ST_NODIRATIME 0x0800 /* do not update directory access times */
#define ST_RELATIME 0x1000 /* update atime relative to mtime/ctime */
+#define ST_NOSYMFOLLOW 0x2000 /* do not follow symlinks */
struct dentry;
extern int vfs_get_fsid(struct dentry *dentry, __kernel_fsid_t *fsid);
diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h
index 96a0240f23fed..dd8306ea336c1 100644
--- a/include/uapi/linux/mount.h
+++ b/include/uapi/linux/mount.h
@@ -16,6 +16,7 @@
#define MS_REMOUNT 32 /* Alter flags of a mounted FS */
#define MS_MANDLOCK 64 /* Allow mandatory locks on an FS */
#define MS_DIRSYNC 128 /* Directory modifications are synchronous */
+#define MS_NOSYMFOLLOW 256 /* Do not follow symlinks */
#define MS_NOATIME 1024 /* Do not update access times. */
#define MS_NODIRATIME 2048 /* Do not update directory access times */
#define MS_BIND 4096
--
2.28.0.297.g1956fa8f8d-goog
Hi Linus,
Please pull the following Kselftest update for Linux 5.9-rc5.
This kselftest fixes update for Linux 5.9-rc5 consists of a single
fix to timers test to disable timeout setting for tests to run and
report accurate results.
diff is attached.
thanks,
-- Shuah
----------------------------------------------------------------
The following changes since commit 9123e3a74ec7b934a4a099e98af6a61c2f80bbf5:
Linux 5.9-rc1 (2020-08-16 13:04:57 -0700)
are available in the Git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
tags/linux-kselftest-5.9-rc5
for you to fetch changes up to 5c1e4f7e9e49b6925b1fb5c507d2c614f3edb292:
selftests/timers: Turn off timeout setting (2020-08-20 15:49:28 -0600)
----------------------------------------------------------------
linux-kselftest-5.9-rc5
This kselftest fixes update for Linux 5.9-rc5 consists of a single
fix to timers test to disable timeout setting for tests to run and
report accurate results.
----------------------------------------------------------------
Po-Hsu Lin (1):
selftests/timers: Turn off timeout setting
tools/testing/selftests/timers/Makefile | 1 +
tools/testing/selftests/timers/settings | 1 +
2 files changed, 2 insertions(+)
create mode 100644 tools/testing/selftests/timers/settings
----------------------------------------------------------------
Changes since v1:
- reworked patches set to use translator
- separated the compat layer into xfrm_compat.c,
compiled under XFRM_USER_COMPAT config
- 32-bit messages now being sent in frag_list (like wext-core does)
- instead of __packed add compat_u64 members in compat structures
- selftest reworked to kselftest lib API
- added netlink dump testing to the selftest
XFRM is disabled for compatible users because of the UABI difference.
The difference is in structures paddings and in the result the size
of netlink messages differ.
Possibility for compatible application to manage xfrm tunnels was
disabled by: the commmit 19d7df69fdb2 ("xfrm: Refuse to insert 32 bit
userspace socket policies on 64 bit systems") and the commit 74005991b78a
("xfrm: Do not parse 32bits compiled xfrm netlink msg on 64bits host").
This is my second attempt to resolve the xfrm/compat problem by adding
the 64=>32 and 32=>64 bit translators those non-visibly to a user
provide translation between compatible user and kernel.
Previous attempt was to interrupt the message ABI according to a syscall
by xfrm_user, which resulted in over-complicated code [1].
Florian Westphal provided the idea of translator and some draft patches
in the discussion. In these patches, his idea is reused and some of his
initial code is also present.
There were a couple of attempts to solve xfrm compat problem:
https://lkml.org/lkml/2017/1/20/733https://patchwork.ozlabs.org/patch/44600/http://netdev.vger.kernel.narkive.com/2Gesykj6/patch-net-next-xfrm-correctl…
All the discussions end in the conclusion that xfrm should have a full
compatible layer to correctly work with 32-bit applications on 64-bit
kernels:
https://lkml.org/lkml/2017/1/23/413https://patchwork.ozlabs.org/patch/433279/
In some recent lkml discussion, Linus said that it's worth to fix this
problem and not giving people an excuse to stay on 32-bit kernel:
https://lkml.org/lkml/2018/2/13/752
There is also an selftest for ipsec tunnels.
It doesn't depend on any library and compat version can be easy
build with: make CFLAGS=-m32 net/ipsec
Patches as a .git branch:
https://github.com/0x7f454c46/linux/tree/xfrm-compat-v2
[1]: https://lkml.kernel.org/r/20180726023144.31066-1-dima@arista.com
Cc: "David S. Miller" <davem(a)davemloft.net>
Cc: Florian Westphal <fw(a)strlen.de>
Cc: Herbert Xu <herbert(a)gondor.apana.org.au>
Cc: Jakub Kicinski <kuba(a)kernel.org>
Cc: Steffen Klassert <steffen.klassert(a)secunet.com>
Cc: Stephen Suryaputra <ssuryaextr(a)gmail.com>
Cc: Dmitry Safonov <0x7f454c46(a)gmail.com>
Cc: netdev(a)vger.kernel.org
Dmitry Safonov (6):
xfrm/compat: Add 64=>32-bit messages translator
xfrm/compat: Attach xfrm dumps to 64=>32 bit translator
netlink/compat: Append NLMSG_DONE/extack to frag_list
xfrm/compat: Add 32=>64-bit messages translator
xfrm/compat: Translate 32-bit user_policy from sockptr
selftest/net/xfrm: Add test for ipsec tunnel
MAINTAINERS | 1 +
include/net/xfrm.h | 32 +
net/netlink/af_netlink.c | 48 +-
net/xfrm/Kconfig | 11 +
net/xfrm/Makefile | 1 +
net/xfrm/xfrm_compat.c | 609 +++++++
net/xfrm/xfrm_state.c | 11 +-
net/xfrm/xfrm_user.c | 79 +-
tools/testing/selftests/net/.gitignore | 1 +
tools/testing/selftests/net/Makefile | 1 +
tools/testing/selftests/net/ipsec.c | 2195 ++++++++++++++++++++++++
11 files changed, 2953 insertions(+), 36 deletions(-)
create mode 100644 net/xfrm/xfrm_compat.c
create mode 100644 tools/testing/selftests/net/ipsec.c
--
2.27.0
As discussed in [1], KUnit tests have hitherto not had a particularly
consistent naming scheme. This adds documentation outlining how tests
and test suites should be named, including how those names should be
used in Kconfig entries and filenames.
[1]:
https://lore.kernel.org/linux-kselftest/202006141005.BA19A9D3@keescook/t/#u
Signed-off-by: David Gow <davidgow(a)google.com>
Reviewed-by: Kees Cook <keescook(a)chromium.org>
---
This is a follow-up v1 to the RFC patch here:
https://lore.kernel.org/linux-kselftest/20200620054944.167330-1-davidgow@go…
There weren't any fundamental objections to the naming guidelines
themselves, so nothing's changed on that front.
Otherwise, changes since the RFC:
- Fixed a bit of space/tab confusion in the index (Thanks, Randy)
- Added some more examples (and some test case examples).
- Added some examples of what not to call subsystems and suites.
- No longer explicitly require "If unsure, put N" in Kconfig entries.
- Minor formatting changes.
Cheers,
-- David
Documentation/dev-tools/kunit/index.rst | 1 +
Documentation/dev-tools/kunit/style.rst | 181 ++++++++++++++++++++++++
2 files changed, 182 insertions(+)
create mode 100644 Documentation/dev-tools/kunit/style.rst
diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst
index e93606ecfb01..c234a3ab3c34 100644
--- a/Documentation/dev-tools/kunit/index.rst
+++ b/Documentation/dev-tools/kunit/index.rst
@@ -11,6 +11,7 @@ KUnit - Unit Testing for the Linux Kernel
usage
kunit-tool
api/index
+ style
faq
What is KUnit?
diff --git a/Documentation/dev-tools/kunit/style.rst b/Documentation/dev-tools/kunit/style.rst
new file mode 100644
index 000000000000..8cad2627924c
--- /dev/null
+++ b/Documentation/dev-tools/kunit/style.rst
@@ -0,0 +1,181 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
+Test Style and Nomenclature
+===========================
+
+Subsystems, Suites, and Tests
+=============================
+
+In order to make tests as easy to find as possible, they're grouped into suites
+and subsystems. A test suite is a group of tests which test a related area of
+the kernel, and a subsystem is a set of test suites which test different parts
+of the same kernel subsystem or driver.
+
+Subsystems
+----------
+
+Every test suite must belong to a subsystem. A subsystem is a collection of one
+or more KUnit test suites which test the same driver or part of the kernel. A
+rule of thumb is that a test subsystem should match a single kernel module. If
+the code being tested can't be compiled as a module, in many cases the subsystem
+should correspond to a directory in the source tree or an entry in the
+MAINTAINERS file. If unsure, follow the conventions set by tests in similar
+areas.
+
+Test subsystems should be named after the code being tested, either after the
+module (wherever possible), or after the directory or files being tested. Test
+subsystems should be named to avoid ambiguity where necessary.
+
+If a test subsystem name has multiple components, they should be separated by
+underscores. *Do not* include "test" or "kunit" directly in the subsystem name
+unless you are actually testing other tests or the kunit framework itself.
+
+Example subsystems could be:
+
+``ext4``
+ Matches the module and filesystem name.
+``apparmor``
+ Matches the module name and LSM name.
+``kasan``
+ Common name for the tool, prominent part of the path ``mm/kasan``
+``snd_hda_codec_hdmi``
+ Has several components (``snd``, ``hda``, ``codec``, ``hdmi``) separated by
+ underscores. Matches the module name.
+
+Avoid names like these:
+
+``linear-ranges``
+ Names should use underscores, not dashes, to separate words. Prefer
+ ``linear_ranges``.
+``qos-kunit-test``
+ As well as using underscores, this name should not have "kunit-test" as a
+ suffix, and ``qos`` is ambiguous as a subsystem name. ``power_qos`` would be a
+ better name.
+``pc_parallel_port``
+ The corresponding module name is ``parport_pc``, so this subsystem should also
+ be named ``parport_pc``.
+
+.. note::
+ The KUnit API and tools do not explicitly know about subsystems. They're
+ simply a way of categorising test suites and naming modules which
+ provides a simple, consistent way for humans to find and run tests. This
+ may change in the future, though.
+
+Suites
+------
+
+KUnit tests are grouped into test suites, which cover a specific area of
+functionality being tested. Test suites can have shared initialisation and
+shutdown code which is run for all tests in the suite.
+Not all subsystems will need to be split into multiple test suites (e.g. simple drivers).
+
+Test suites are named after the subsystem they are part of. If a subsystem
+contains several suites, the specific area under test should be appended to the
+subsystem name, separated by an underscore.
+
+The full test suite name (including the subsystem name) should be specified as
+the ``.name`` member of the ``kunit_suite`` struct, and forms the base for the
+module name (see below).
+
+Example test suites could include:
+
+``ext4_inode``
+ Part of the ``ext4`` subsystem, testing the ``inode`` area.
+``kunit_try_catch``
+ Part of the ``kunit`` implementation itself, testing the ``try_catch`` area.
+``apparmor_property_entry``
+ Part of the ``apparmor`` subsystem, testing the ``property_entry`` area.
+``kasan``
+ The ``kasan`` subsystem has only one suite, so the suite name is the same as
+ the subsystem name.
+
+Avoid names like:
+
+``ext4_ext4_inode``
+ There's no reason to state the subsystem twice.
+``property_entry``
+ The suite name is ambiguous without the subsystem name.
+``kasan_unit_test``
+ Because there is only one suite in the ``kasan`` subsystem, the suite should
+ just be called ``kasan``. There's no need to redundantly add ``unit_test``.
+
+Test Cases
+----------
+
+Individual tests consist of a single function which tests a constrained
+codepath, property, or function. In the test output, individual tests' results
+will show up as subtests of the suite's results.
+
+Tests should be named after what they're testing. This is often the name of the
+function being tested, with a description of the input or codepath being tested.
+As tests are C functions, they should be named and written in accordance with
+the kernel coding style.
+
+.. note::
+ As tests are themselves functions, their names cannot conflict with
+ other C identifiers in the kernel. This may require some creative
+ naming. It's a good idea to make your test functions `static` to avoid
+ polluting the global namespace.
+
+Example test names include:
+
+``unpack_u32_with_null_name``
+ Tests the ``unpack_u32`` function when a NULL name is passed in.
+``test_list_splice``
+ Tests the ``list_splice`` macro. It has the prefix ``test_`` to avoid a
+ name conflict with the macro itself.
+
+
+Should it be necessary to refer to a test outside the context of its test suite,
+the *fully-qualified* name of a test should be the suite name followed by the
+test name, separated by a colon (i.e. ``suite:test``).
+
+Test Kconfig Entries
+====================
+
+Every test suite should be tied to a Kconfig entry.
+
+This Kconfig entry must:
+
+* be named ``CONFIG_<name>_KUNIT_TEST``: where <name> is the name of the test
+ suite.
+* be listed either alongside the config entries for the driver/subsystem being
+ tested, or be under [Kernel Hacking]→[Kernel Testing and Coverage]
+* depend on ``CONFIG_KUNIT``
+* be visible only if ``CONFIG_KUNIT_ALL_TESTS`` is not enabled.
+* have a default value of ``CONFIG_KUNIT_ALL_TESTS``.
+* have a brief description of KUnit in the help text
+
+Unless there's a specific reason not to (e.g. the test is unable to be built as
+a module), Kconfig entries for tests should be tristate.
+
+An example Kconfig entry:
+
+.. code-block:: none
+
+ config FOO_KUNIT_TEST
+ tristate "KUnit test for foo" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ This builds unit tests for foo.
+
+ For more information on KUnit and unit tests in general, please refer
+ to the KUnit documentation in Documentation/dev-tools/kunit
+
+ If unsure, say N
+
+
+Test Filenames
+==============
+
+Where possible, test suites should be placed in a separate source file in the
+same directory as the code being tested.
+
+This file should be named ``<suite>_kunit.c``. It may make sense to strip
+excessive namespacing from the source filename (e.g., ``firmware_kunit.c`` instead of
+``<drivername>_firmware.c``), but please ensure the module name does contain the
+full suite name.
+
+
--
2.27.0.212.ge8ba1cc988-goog
