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 ============================
 Tips For Running KUnit Tests
 ============================
 
 Using ``kunit.py run`` ("kunit tool")
 =====================================
 
 Running from any directory
 --------------------------
 
 It can be handy to create a bash function like:
 
 .. code-block:: bash
 
         function run_kunit() {
           ( cd "$(git rev-parse --show-toplevel)" && ./tools/testing/kunit/kunit.py run "$@" )
         }
 
 .. note::
         Early versions of ``kunit.py`` (before 5.6) didn't work unless run from
         the kernel root, hence the use of a subshell and ``cd``.
 
 Running a subset of tests
 -------------------------
 
 ``kunit.py run`` accepts an optional glob argument to filter tests. The format
 is ``"<suite_glob>[.test_glob]"``.
 
 Say that we wanted to run the sysctl tests, we could do so via:
 
 .. code-block:: bash
 
         $ echo -e 'CONFIG_KUNIT=y\nCONFIG_KUNIT_ALL_TESTS=y' > .kunit/.kunitconfig
         $ ./tools/testing/kunit/kunit.py run 'sysctl*'
 
 We can filter down to just the "write" tests via:
 
 .. code-block:: bash
 
         $ echo -e 'CONFIG_KUNIT=y\nCONFIG_KUNIT_ALL_TESTS=y' > .kunit/.kunitconfig
         $ ./tools/testing/kunit/kunit.py run 'sysctl*.*write*'
 
 We're paying the cost of building more tests than we need this way, but it's
 easier than fiddling with ``.kunitconfig`` files or commenting out
 ``kunit_suite``'s.
 
 However, if we wanted to define a set of tests in a less ad hoc way, the next
 tip is useful.
 
 Defining a set of tests
 -----------------------
 
 ``kunit.py run`` (along with ``build``, and ``config``) supports a
 ``--kunitconfig`` flag. So if you have a set of tests that you want to run on a
 regular basis (especially if they have other dependencies), you can create a
 specific ``.kunitconfig`` for them.
 
 E.g. kunit has one for its tests:
 
 .. code-block:: bash
 
         $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit/.kunitconfig
 
 Alternatively, if you're following the convention of naming your
 file ``.kunitconfig``, you can just pass in the dir, e.g.
 
 .. code-block:: bash
 
         $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit
 
 .. note::
         This is a relatively new feature (5.12+) so we don't have any
         conventions yet about on what files should be checked in versus just
         kept around locally. It's up to you and your maintainer to decide if a
         config is useful enough to submit (and therefore have to maintain).
 
 .. note::
         Having ``.kunitconfig`` fragments in a parent and child directory is
         iffy. There's discussion about adding an "import" statement in these
         files to make it possible to have a top-level config run tests from all
         child directories. But that would mean ``.kunitconfig`` files are no
         longer just simple .config fragments.
 
         One alternative would be to have kunit tool recursively combine configs
         automagically, but tests could theoretically depend on incompatible
         options, so handling that would be tricky.
 
 Setting kernel commandline parameters
 -------------------------------------
 
 You can use ``--kernel_args`` to pass arbitrary kernel arguments, e.g.
 
 .. code-block:: bash
 
         $ ./tools/testing/kunit/kunit.py run --kernel_args=param=42 --kernel_args=param2=false
 
 
 Generating code coverage reports under UML
 ------------------------------------------
 
 .. note::
         TODO(brendanhiggins@google.com): There are various issues with UML and
         versions of gcc 7 and up. You're likely to run into missing ``.gcda``
         files or compile errors.
 
 This is different from the "normal" way of getting coverage information that is
 documented in Documentation/dev-tools/gcov.rst.
 
 Instead of enabling ``CONFIG_GCOV_KERNEL=y``, we can set these options:
 
 .. code-block:: none
 
         CONFIG_DEBUG_KERNEL=y
         CONFIG_DEBUG_INFO=y
         CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
         CONFIG_GCOV=y
 
 
 Putting it together into a copy-pastable sequence of commands:
 
 .. code-block:: bash
 
         # Append coverage options to the current config
         $ ./tools/testing/kunit/kunit.py run --kunitconfig=.kunit/ --kunitconfig=tools/testing/kunit/configs/coverage_uml.config
         # Extract the coverage information from the build dir (.kunit/)
         $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/
 
         # From here on, it's the same process as with CONFIG_GCOV_KERNEL=y
         # E.g. can generate an HTML report in a tmp dir like so:
         $ genhtml -o /tmp/coverage_html coverage.info
 
 
 If your installed version of gcc doesn't work, you can tweak the steps:
 
 .. code-block:: bash
 
         $ ./tools/testing/kunit/kunit.py run --make_options=CC=/usr/bin/gcc-6
         $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ --gcov-tool=/usr/bin/gcov-6
 
 
 Running tests manually
 ======================
 
 Running tests without using ``kunit.py run`` is also an important use case.
 Currently it's your only option if you want to test on architectures other than
 UML.
 
 As running the tests under UML is fairly straightforward (configure and compile
 the kernel, run the ``./linux`` binary), this section will focus on testing
 non-UML architectures.
 
 
 Running built-in tests
 ----------------------
 
 When setting tests to ``=y``, the tests will run as part of boot and print
 results to dmesg in TAP format. So you just need to add your tests to your
 ``.config``, build and boot your kernel as normal.
 
 So if we compiled our kernel with:
 
 .. code-block:: none
 
         CONFIG_KUNIT=y
         CONFIG_KUNIT_EXAMPLE_TEST=y
 
 Then we'd see output like this in dmesg signaling the test ran and passed:
 
 .. code-block:: none
 
         TAP version 14
         1..1
             # Subtest: example
             1..1
             # example_simple_test: initializing
             ok 1 - example_simple_test
         ok 1 - example
 
 Running tests as modules
 ------------------------
 
 Depending on the tests, you can build them as loadable modules.
 
 For example, we'd change the config options from before to
 
 .. code-block:: none
 
         CONFIG_KUNIT=y
         CONFIG_KUNIT_EXAMPLE_TEST=m
 
 Then after booting into our kernel, we can run the test via
 
 .. code-block:: none
 
         $ modprobe kunit-example-test
 
 This will then cause it to print TAP output to stdout.
 
 .. note::
         The ``modprobe`` will *not* have a non-zero exit code if any test
         failed (as of 5.13). But ``kunit.py parse`` would, see below.
 
 .. note::
         You can set ``CONFIG_KUNIT=m`` as well, however, some features will not
         work and thus some tests might break. Ideally tests would specify they
         depend on ``KUNIT=y`` in their ``Kconfig``'s, but this is an edge case
         most test authors won't think about.
         As of 5.13, the only difference is that ``current->kunit_test`` will
         not exist.
 
 Pretty-printing results
 -----------------------
 
 You can use ``kunit.py parse`` to parse dmesg for test output and print out
 results in the same familiar format that ``kunit.py run`` does.
 
 .. code-block:: bash
 
         $ ./tools/testing/kunit/kunit.py parse /var/log/dmesg
 
 
 Retrieving per suite results
 ----------------------------
 
 Regardless of how you're running your tests, you can enable
 ``CONFIG_KUNIT_DEBUGFS`` to expose per-suite TAP-formatted results:
 
 .. code-block:: none
 
         CONFIG_KUNIT=y
         CONFIG_KUNIT_EXAMPLE_TEST=m
         CONFIG_KUNIT_DEBUGFS=y
 
 The results for each suite will be exposed under
 ``/sys/kernel/debug/kunit/<suite>/results``.
 So using our example config:
 
 .. code-block:: bash
 
         $ modprobe kunit-example-test > /dev/null
         $ cat /sys/kernel/debug/kunit/example/results
         ... <TAP output> ...
 
         # After removing the module, the corresponding files will go away
         $ modprobe -r kunit-example-test
         $ cat /sys/kernel/debug/kunit/example/results
         /sys/kernel/debug/kunit/example/results: No such file or directory
 
 Generating code coverage reports
 --------------------------------
 
 See Documentation/dev-tools/gcov.rst for details on how to do this.
 
 The only vaguely KUnit-specific advice here is that you probably want to build
 your tests as modules. That way you can isolate the coverage from tests from
 other code executed during boot, e.g.
 
 .. code-block:: bash
 
         # Reset coverage counters before running the test.
         $ echo 0 > /sys/kernel/debug/gcov/reset
         $ modprobe kunit-example-test

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