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diff --git a/Documentation/dev-tools/kunit/start.rst b/Documentation/dev-tools/kunit/start.rst new file mode 100644 index 000000000000..aeeddfafeea2 --- /dev/null +++ b/Documentation/dev-tools/kunit/start.rst @@ -0,0 +1,180 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============== +Getting Started +=============== + +Installing dependencies +======================= +KUnit has the same dependencies as the Linux kernel. As long as you can build +the kernel, you can run KUnit. + +KUnit Wrapper +============= +Included with KUnit is a simple Python wrapper that helps format the output to +easily use and read KUnit output. It handles building and running the kernel, as +well as formatting the output. + +The wrapper can be run with: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py run + +Creating a kunitconfig +====================== +The Python script is a thin wrapper around Kbuild as such, it needs to be +configured with a ``kunitconfig`` file. This file essentially contains the +regular Kernel config, with the specific test targets as well. + +.. code-block:: bash + + git clone -b master https://kunit.googlesource.com/kunitconfig $PATH_TO_KUNITCONFIG_REPO + cd $PATH_TO_LINUX_REPO + ln -s $PATH_TO_KUNIT_CONFIG_REPO/kunitconfig kunitconfig + +You may want to add kunitconfig to your local gitignore. + +Verifying KUnit Works +--------------------- + +To make sure that everything is set up correctly, simply invoke the Python +wrapper from your kernel repo: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py run + +.. note:: + You may want to run ``make mrproper`` first. + +If everything worked correctly, you should see the following: + +.. code-block:: bash + + Generating .config ... + Building KUnit Kernel ... + Starting KUnit Kernel ... + +followed by a list of tests that are run. All of them should be passing. + +.. note:: + Because it is building a lot of sources for the first time, the ``Building + kunit kernel`` step may take a while. + +Writing your first test +======================= + +In your kernel repo let's add some code that we can test. Create a file +``drivers/misc/example.h`` with the contents: + +.. code-block:: c + + int misc_example_add(int left, int right); + +create a file ``drivers/misc/example.c``: + +.. code-block:: c + + #include <linux/errno.h> + + #include "example.h" + + int misc_example_add(int left, int right) + { + return left + right; + } + +Now add the following lines to ``drivers/misc/Kconfig``: + +.. code-block:: kconfig + + config MISC_EXAMPLE + bool "My example" + +and the following lines to ``drivers/misc/Makefile``: + +.. code-block:: make + + obj-$(CONFIG_MISC_EXAMPLE) += example.o + +Now we are ready to write the test. The test will be in +``drivers/misc/example-test.c``: + +.. code-block:: c + + #include <kunit/test.h> + #include "example.h" + + /* Define the test cases. */ + + static void misc_example_add_test_basic(struct kunit *test) + { + KUNIT_EXPECT_EQ(test, 1, misc_example_add(1, 0)); + KUNIT_EXPECT_EQ(test, 2, misc_example_add(1, 1)); + KUNIT_EXPECT_EQ(test, 0, misc_example_add(-1, 1)); + KUNIT_EXPECT_EQ(test, INT_MAX, misc_example_add(0, INT_MAX)); + KUNIT_EXPECT_EQ(test, -1, misc_example_add(INT_MAX, INT_MIN)); + } + + static void misc_example_test_failure(struct kunit *test) + { + KUNIT_FAIL(test, "This test never passes."); + } + + static struct kunit_case misc_example_test_cases[] = { + KUNIT_CASE(misc_example_add_test_basic), + KUNIT_CASE(misc_example_test_failure), + {} + }; + + static struct kunit_suite misc_example_test_suite = { + .name = "misc-example", + .test_cases = misc_example_test_cases, + }; + kunit_test_suite(misc_example_test_suite); + +Now add the following to ``drivers/misc/Kconfig``: + +.. code-block:: kconfig + + config MISC_EXAMPLE_TEST + bool "Test for my example" + depends on MISC_EXAMPLE && KUNIT + +and the following to ``drivers/misc/Makefile``: + +.. code-block:: make + + obj-$(CONFIG_MISC_EXAMPLE_TEST) += example-test.o + +Now add it to your ``kunitconfig``: + +.. code-block:: none + + CONFIG_MISC_EXAMPLE=y + CONFIG_MISC_EXAMPLE_TEST=y + +Now you can run the test: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py + +You should see the following failure: + +.. code-block:: none + + ... + [16:08:57] [PASSED] misc-example:misc_example_add_test_basic + [16:08:57] [FAILED] misc-example:misc_example_test_failure + [16:08:57] EXPECTATION FAILED at drivers/misc/example-test.c:17 + [16:08:57] This test never passes. + ... + +Congrats! You just wrote your first KUnit test! + +Next Steps +========== +* Check out the :doc:`usage` page for a more + in-depth explanation of KUnit. |