-----Original Message----- From: David Gow
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.
Signed-off-by: David Gow davidgow@google.com Reviewed-by: Kees Cook keescook@chromium.org Reviewed-by: Brendan Higgins brendanhiggins@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@go...
- 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@goo...
- 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'resimply a way of categorising test suites and naming modules whichprovides a simple, consistent way for humans to find and run tests. Thismay 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 withother C identifiers in the kernel. This may require some creativenaming. It's a good idea to make your test functions `static` to avoidpolluting 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_TESTtristate "KUnit test for foo" if !KUNIT_ALL_TESTSdepends on KUNITdefault KUNIT_ALL_TESTShelpThis builds unit tests for foo.For more information on KUnit and unit tests in general, please referto the KUnit documentation in Documentation/dev-tools/kunitIf 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
Looks good! I know this was a lot of hard work to get consensus here. This will help a lot for test frameworks to have consistent and persistent, fully-qualified names for testcases. Good job!
Reviewed-by: Tim Bird tim.bird@sony.com
-- Tim