1 .. SPDX-License-Identifier: GPL-2.0
7 Installing Dependencies
8 =======================
9 KUnit has the same dependencies as the Linux kernel. As long as you can
10 build the kernel, you can run KUnit.
12 Running tests with kunit_tool
13 =============================
14 kunit_tool is a Python script, which configures and builds a kernel, runs
15 tests, and formats the test results. From the kernel repository, you
20 ./tools/testing/kunit/kunit.py run
23 You may see the following error:
24 "The source tree is not clean, please run 'make ARCH=um mrproper'"
26 This happens because internally kunit.py specifies ``.kunit``
27 (default option) as the build directory in the command ``make O=output/dir``
28 through the argument ``--build_dir``. Hence, before starting an
29 out-of-tree build, the source tree must be clean.
31 There is also the same caveat mentioned in the "Build directory for
32 the kernel" section of the :doc:`admin-guide </admin-guide/README>`,
33 that is, its use, it must be used for all invocations of ``make``.
34 The good news is that it can indeed be solved by running
35 ``make ARCH=um mrproper``, just be aware that this will delete the
36 current configuration and all generated files.
38 If everything worked correctly, you should see the following:
42 Configuring KUnit Kernel ...
43 Building KUnit Kernel ...
44 Starting KUnit Kernel ...
46 The tests will pass or fail.
49 Because it is building a lot of sources for the first time,
50 the ``Building KUnit Kernel`` step may take a while.
52 For detailed information on this wrapper, see:
53 Documentation/dev-tools/kunit/run_wrapper.rst.
55 Creating a ``.kunitconfig``
56 ---------------------------
58 By default, kunit_tool runs a selection of tests. However, you can specify which
59 unit tests to run by creating a ``.kunitconfig`` file with kernel config options
60 that enable only a specific set of tests and their dependencies.
61 The ``.kunitconfig`` file contains a list of kconfig options which are required
62 to run the desired targets. The ``.kunitconfig`` also contains any other test
63 specific config options, such as test dependencies. For example: the
64 ``FAT_FS`` tests - ``FAT_KUNIT_TEST``, depends on
65 ``FAT_FS``. ``FAT_FS`` can be enabled by selecting either ``MSDOS_FS``
66 or ``VFAT_FS``. To run ``FAT_KUNIT_TEST``, the ``.kunitconfig`` has:
72 CONFIG_FAT_KUNIT_TEST=y
74 1. A good starting point for the ``.kunitconfig`` is the KUnit default config.
75 You can generate it by running:
79 cd $PATH_TO_LINUX_REPO
80 tools/testing/kunit/kunit.py config
81 cat .kunit/.kunitconfig
84 ``.kunitconfig`` lives in the ``--build_dir`` used by kunit.py, which is
85 ``.kunit`` by default.
88 You may want to remove CONFIG_KUNIT_ALL_TESTS from the ``.kunitconfig`` as
89 it will enable a number of additional tests that you may not want.
91 2. You can then add any other Kconfig options, for example:
95 CONFIG_LIST_KUNIT_TEST=y
97 Before running the tests, kunit_tool ensures that all config options
98 set in ``.kunitconfig`` are set in the kernel ``.config``. It will warn
99 you if you have not included dependencies for the options used.
102 If you change the ``.kunitconfig``, kunit.py will trigger a rebuild of the
103 ``.config`` file. But you can edit the ``.config`` file directly or with
104 tools like ``make menuconfig O=.kunit``. As long as its a superset of
105 ``.kunitconfig``, kunit.py won't overwrite your changes.
108 Running Tests without the KUnit Wrapper
109 =======================================
110 If you do not want to use the KUnit Wrapper (for example: you want code
111 under test to integrate with other systems, or use a different/
112 unsupported architecture or configuration), KUnit can be included in
113 any kernel, and the results are read out and parsed manually.
116 ``CONFIG_KUNIT`` should not be enabled in a production environment.
117 Enabling KUnit disables Kernel Address-Space Layout Randomization
118 (KASLR), and tests may affect the state of the kernel in ways not
119 suitable for production.
121 Configuring the Kernel
122 ----------------------
123 To enable KUnit itself, you need to enable the ``CONFIG_KUNIT`` Kconfig
124 option (under Kernel Hacking/Kernel Testing and Coverage in
125 ``menuconfig``). From there, you can enable any KUnit tests. They
126 usually have config options ending in ``_KUNIT_TEST``.
128 KUnit and KUnit tests can be compiled as modules. The tests in a module
129 will run when the module is loaded.
131 Running Tests (without KUnit Wrapper)
132 -------------------------------------
133 Build and run your kernel. In the kernel log, the test output is printed
134 out in the TAP format. This will only happen by default if KUnit/tests
135 are built-in. Otherwise the module will need to be loaded.
138 Some lines and/or data may get interspersed in the TAP output.
140 Writing Your First Test
141 =======================
142 In your kernel repository, let's add some code that we can test.
144 1. Create a file ``drivers/misc/example.h``, which includes:
148 int misc_example_add(int left, int right);
150 2. Create a file ``drivers/misc/example.c``, which includes:
154 #include <linux/errno.h>
158 int misc_example_add(int left, int right)
163 3. Add the following lines to ``drivers/misc/Kconfig``:
165 .. code-block:: kconfig
170 4. Add the following lines to ``drivers/misc/Makefile``:
174 obj-$(CONFIG_MISC_EXAMPLE) += example.o
176 Now we are ready to write the test cases.
178 1. Add the below test case in ``drivers/misc/example_test.c``:
182 #include <kunit/test.h>
185 /* Define the test cases. */
187 static void misc_example_add_test_basic(struct kunit *test)
189 KUNIT_EXPECT_EQ(test, 1, misc_example_add(1, 0));
190 KUNIT_EXPECT_EQ(test, 2, misc_example_add(1, 1));
191 KUNIT_EXPECT_EQ(test, 0, misc_example_add(-1, 1));
192 KUNIT_EXPECT_EQ(test, INT_MAX, misc_example_add(0, INT_MAX));
193 KUNIT_EXPECT_EQ(test, -1, misc_example_add(INT_MAX, INT_MIN));
196 static void misc_example_test_failure(struct kunit *test)
198 KUNIT_FAIL(test, "This test never passes.");
201 static struct kunit_case misc_example_test_cases[] = {
202 KUNIT_CASE(misc_example_add_test_basic),
203 KUNIT_CASE(misc_example_test_failure),
207 static struct kunit_suite misc_example_test_suite = {
208 .name = "misc-example",
209 .test_cases = misc_example_test_cases,
211 kunit_test_suite(misc_example_test_suite);
213 2. Add the following lines to ``drivers/misc/Kconfig``:
215 .. code-block:: kconfig
217 config MISC_EXAMPLE_TEST
218 tristate "Test for my example" if !KUNIT_ALL_TESTS
219 depends on MISC_EXAMPLE && KUNIT=y
220 default KUNIT_ALL_TESTS
222 3. Add the following lines to ``drivers/misc/Makefile``:
226 obj-$(CONFIG_MISC_EXAMPLE_TEST) += example_test.o
228 4. Add the following lines to ``.kunitconfig``:
232 CONFIG_MISC_EXAMPLE=y
233 CONFIG_MISC_EXAMPLE_TEST=y
239 ./tools/testing/kunit/kunit.py run
241 You should see the following failure:
246 [16:08:57] [PASSED] misc-example:misc_example_add_test_basic
247 [16:08:57] [FAILED] misc-example:misc_example_test_failure
248 [16:08:57] EXPECTATION FAILED at drivers/misc/example-test.c:17
249 [16:08:57] This test never passes.
252 Congrats! You just wrote your first KUnit test.
257 * Documentation/dev-tools/kunit/architecture.rst - KUnit architecture.
258 * Documentation/dev-tools/kunit/run_wrapper.rst - run kunit_tool.
259 * Documentation/dev-tools/kunit/run_manual.rst - run tests without kunit_tool.
260 * Documentation/dev-tools/kunit/usage.rst - write tests.
261 * Documentation/dev-tools/kunit/tips.rst - best practices with
263 * Documentation/dev-tools/kunit/api/index.rst - KUnit APIs
265 * Documentation/dev-tools/kunit/faq.rst - KUnit common questions and