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+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
+Test Style and Nomenclature
+===========================
+
+To make finding, writing, and using KUnit tests as simple as possible, it is
+strongly encouraged that they are named and written according to the guidelines
+below. While it is 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 is recommended that you only deviate from these guidelines when:
+
+1. Porting tests to KUnit which are already known with an existing name.
+2. Writing tests which would cause serious problems if automatically run. For
+ example, non-deterministically producing false positives or negatives, or
+ taking a long time to run.
+
+Subsystems, Suites, and Tests
+=============================
+
+To make tests easy to find, they are grouped into suites and subsystems. A test
+suite is a group of tests which test a related area of the kernel. A subsystem
+is a set of test suites which test different parts of a kernel subsystem
+or a 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
+test subsystem should match a single kernel module. If the code being tested
+cannot 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 we are actually testing other tests or the kunit framework itself. For
+example, subsystems could be called:
+
+``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 as shown in examples below:
+
+``linear-ranges``
+ Names should use underscores, not dashes, to separate words. Prefer
+ ``linear_ranges``.
+``qos-kunit-test``
+ This name should use underscores, and not have "kunit-test" as a
+ suffix. ``qos`` is also ambiguous as a subsystem name, because several parts
+ of the kernel have a ``qos`` subsystem. ``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 are
+ a way of categorizing test suites and naming modules which provides a
+ simple, consistent way for humans to find and run tests. This may change
+ in the future.
+
+Suites
+------
+
+KUnit tests are grouped into test suites, which cover a specific area of
+functionality being tested. Test suites can have shared initialization and
+shutdown code which is run for all tests in the suite. Not all subsystems need
+to be split into multiple test suites (for example, 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 (for example, 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. For 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, for example:
+
+``ext4_ext4_inode``
+ There is 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 as ``kasan``. Do not redundantly add
+ ``integration_test``. It should be a separate test suite. For example, if the
+ unit tests are added, then that suite could be named as ``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, an individual test's
+results will show up as subtests of the suite's results.
+
+Tests should be named after what they are 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 is 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.
+
+If we are not able to meet above conditions (for example, the test is unable to
+be built as a module), Kconfig entries for tests should be tristate.
+
+For example, a Kconfig entry might look like:
+
+.. 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 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.
+
+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.