WSL2-Linux-Kernel/Documentation/dev-tools/kselftest.rst

======================
Linux Kernel Selftests
======================

The kernel contains a set of "self tests" under the tools/testing/selftests/
directory. These are intended to be small tests to exercise individual code
paths in the kernel. Tests are intended to be run after building, installing
and booting a kernel.

On some systems, hot-plug tests could hang forever waiting for cpu and
memory to be ready to be offlined. A special hot-plug target is created
to run full range of hot-plug tests. In default mode, hot-plug tests run
in safe mode with a limited scope. In limited mode, cpu-hotplug test is
run on a single cpu as opposed to all hotplug capable cpus, and memory
hotplug test is run on 2% of hotplug capable memory instead of 10%.

Running the selftests (hotplug tests are run in limited mode)
=============================================================

To build the tests::

  $ make -C tools/testing/selftests

To run the tests::

  $ make -C tools/testing/selftests run_tests

To build and run the tests with a single command, use::

  $ make kselftest

Note that some tests will require root privileges.

Build and run from user specific object directory (make O=dir)::

  $ make O=/tmp/kselftest kselftest

Build and run KBUILD_OUTPUT directory (make KBUILD_OUTPUT=)::

  $ make KBUILD_OUTPUT=/tmp/kselftest kselftest

The above commands run the tests and print pass/fail summary to make it
easier to understand the test results. Please find the detailed individual
test results for each test in /tmp/testname file(s).

Running a subset of selftests
=============================

You can use the "TARGETS" variable on the make command line to specify
single test to run, or a list of tests to run.

To run only tests targeted for a single subsystem::

  $ make -C tools/testing/selftests TARGETS=ptrace run_tests

You can specify multiple tests to build and run::

  $  make TARGETS="size timers" kselftest

Build and run from user specific object directory (make O=dir)::

  $ make O=/tmp/kselftest TARGETS="size timers" kselftest

Build and run KBUILD_OUTPUT directory (make KBUILD_OUTPUT=)::

  $ make KBUILD_OUTPUT=/tmp/kselftest TARGETS="size timers" kselftest

The above commands run the tests and print pass/fail summary to make it
easier to understand the test results. Please find the detailed individual
test results for each test in /tmp/testname file(s).

See the top-level tools/testing/selftests/Makefile for the list of all
possible targets.

Running the full range hotplug selftests
========================================

To build the hotplug tests::

  $ make -C tools/testing/selftests hotplug

To run the hotplug tests::

  $ make -C tools/testing/selftests run_hotplug

Note that some tests will require root privileges.


Install selftests
=================

You can use kselftest_install.sh tool installs selftests in default
location which is tools/testing/selftests/kselftest or a user specified
location.

To install selftests in default location::

   $ cd tools/testing/selftests
   $ ./kselftest_install.sh

To install selftests in a user specified location::

   $ cd tools/testing/selftests
   $ ./kselftest_install.sh install_dir

Running installed selftests
===========================

Kselftest install as well as the Kselftest tarball provide a script
named "run_kselftest.sh" to run the tests.

You can simply do the following to run the installed Kselftests. Please
note some tests will require root privileges::

   $ cd kselftest
   $ ./run_kselftest.sh

Contributing new tests
======================

In general, the rules for selftests are

 * Do as much as you can if you're not root;

 * Don't take too long;

 * Don't break the build on any architecture, and

 * Don't cause the top-level "make run_tests" to fail if your feature is
   unconfigured.

Contributing new tests (details)
================================

 * Use TEST_GEN_XXX if such binaries or files are generated during
   compiling.

   TEST_PROGS, TEST_GEN_PROGS mean it is the executable tested by
   default.

   TEST_CUSTOM_PROGS should be used by tests that require custom build
   rule and prevent common build rule use.

   TEST_PROGS are for test shell scripts. Please ensure shell script has
   its exec bit set. Otherwise, lib.mk run_tests will generate a warning.

   TEST_CUSTOM_PROGS and TEST_PROGS will be run by common run_tests.

   TEST_PROGS_EXTENDED, TEST_GEN_PROGS_EXTENDED mean it is the
   executable which is not tested by default.
   TEST_FILES, TEST_GEN_FILES mean it is the file which is used by
   test.

Test Harness
============

The kselftest_harness.h file contains useful helpers to build tests.  The tests
from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as example.

Example
-------

.. kernel-doc:: tools/testing/selftests/kselftest_harness.h
    :doc: example


Helpers
-------

.. kernel-doc:: tools/testing/selftests/kselftest_harness.h
    :functions: TH_LOG TEST TEST_SIGNAL FIXTURE FIXTURE_DATA FIXTURE_SETUP
                FIXTURE_TEARDOWN TEST_F TEST_HARNESS_MAIN

Operators
---------

.. kernel-doc:: tools/testing/selftests/kselftest_harness.h
    :doc: operators

.. kernel-doc:: tools/testing/selftests/kselftest_harness.h
    :functions: ASSERT_EQ ASSERT_NE ASSERT_LT ASSERT_LE ASSERT_GT ASSERT_GE
                ASSERT_NULL ASSERT_TRUE ASSERT_NULL ASSERT_TRUE ASSERT_FALSE
                ASSERT_STREQ ASSERT_STRNE EXPECT_EQ EXPECT_NE EXPECT_LT
                EXPECT_LE EXPECT_GT EXPECT_GE EXPECT_NULL EXPECT_TRUE
                EXPECT_FALSE EXPECT_STREQ EXPECT_STRNE