Date:   Tue, 25 Jul 2023 16:42:03 +0800
From:   David Gow <davidgow@...gle.com>
To:     Rae Moar <rmoar@...gle.com>
Cc:     shuah@...nel.org, dlatypov@...gle.com, brendan.higgins@...ux.dev,
        linux-kselftest@...r.kernel.org, kunit-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, keescook@...omium.org,
        linux-hardening@...r.kernel.org, jstultz@...gle.com,
        tglx@...utronix.de, sboyd@...nel.org
Subject: Re: [PATCH v2 9/9] kunit: Add documentation of KUnit test attributes

On Tue, 25 Jul 2023 at 00:31, Rae Moar <rmoar@...gle.com> wrote:
>
> Add documentation on the use of test attributes under the section "Tips for
> Running KUnit Tests" in the KUnit docs.
>
> Documentation includes three sections on how to mark tests with attributes,
> how attributes are reported, and how the user can filter tests using test
> attributes.
>
> Reviewed-by: David Gow <davidgow@...gle.com>
> Signed-off-by: Rae Moar <rmoar@...gle.com>
> ---

This still looks good, but an idea for an improvement (either in this
patch or a future series) would be to add some docs for --filter and
--filter_action to run_wrapper.rst, which has a list of kunit.py
options.

> Changes since v1:
> - No changes.
>
> Changes since RFC v2:
> - Add comment on KUNIT_CASE_SLOW() to documentation.
> - Add comment on how to expose raw kernel output.
> - Remove an extra line at the end of file.
>
> Changes since RFC v1:
> - This is a new patch.
>
>  .../dev-tools/kunit/running_tips.rst          | 166 ++++++++++++++++++
>  1 file changed, 166 insertions(+)
>
> diff --git a/Documentation/dev-tools/kunit/running_tips.rst b/Documentation/dev-tools/kunit/running_tips.rst
> index 8e8c493f17d1..766f9cdea0fa 100644
> --- a/Documentation/dev-tools/kunit/running_tips.rst
> +++ b/Documentation/dev-tools/kunit/running_tips.rst
> @@ -262,3 +262,169 @@ other code executed during boot, e.g.
>         # Reset coverage counters before running the test.
>         $ echo 0 > /sys/kernel/debug/gcov/reset
>         $ modprobe kunit-example-test
> +
> +
> +Test Attributes and Filtering
> +=============================
> +
> +Test suites and cases can be marked with test attributes, such as speed of
> +test. These attributes will later be printed in test output and can be used to
> +filter test execution.
> +
> +Marking Test Attributes
> +-----------------------
> +
> +Tests are marked with an attribute by including a ``kunit_attributes`` object
> +in the test definition.
> +
> +Test cases can be marked using the ``KUNIT_CASE_ATTR(test_name, attributes)``
> +macro to define the test case instead of ``KUNIT_CASE(test_name)``.
> +
> +.. code-block:: c
> +
> +       static const struct kunit_attributes example_attr = {
> +               .speed = KUNIT_VERY_SLOW,
> +       };
> +
> +       static struct kunit_case example_test_cases[] = {
> +               KUNIT_CASE_ATTR(example_test, example_attr),
> +       };
> +
> +.. note::
> +       To mark a test case as slow, you can also use ``KUNIT_CASE_SLOW(test_name)``.
> +       This is a helpful macro as the slow attribute is the most commonly used.
> +
> +Test suites can be marked with an attribute by setting the "attr" field in the
> +suite definition.
> +
> +.. code-block:: c
> +
> +       static const struct kunit_attributes example_attr = {
> +               .speed = KUNIT_VERY_SLOW,
> +       };
> +
> +       static struct kunit_suite example_test_suite = {
> +               ...,
> +               .attr = example_attr,
> +       };
> +
> +.. note::
> +       Not all attributes need to be set in a ``kunit_attributes`` object. Unset
> +       attributes will remain uninitialized and act as though the attribute is set
> +       to 0 or NULL. Thus, if an attribute is set to 0, it is treated as unset.
> +       These unset attributes will not be reported and may act as a default value
> +       for filtering purposes.
> +
> +Reporting Attributes
> +--------------------
> +
> +When a user runs tests, attributes will be present in the raw kernel output (in
> +KTAP format). Note that attributes will be hidden by default in kunit.py output
> +for all passing tests but the raw kernel output can be accessed using the
> +``--raw_output`` flag. This is an example of how test attributes for test cases
> +will be formatted in kernel output:
> +
> +.. code-block:: none
> +
> +       # example_test.speed: slow
> +       ok 1 example_test
> +
> +This is an example of how test attributes for test suites will be formatted in
> +kernel output:
> +
> +.. code-block:: none
> +
> +         KTAP version 2
> +         # Subtest: example_suite
> +         # module: kunit_example_test
> +         1..3
> +         ...
> +       ok 1 example_suite
> +
> +Additionally, users can output a full attribute report of tests with their
> +attributes, using the command line flag ``--list_tests_attr``:
> +
> +.. code-block:: bash
> +
> +       kunit.py run "example" --list_tests_attr
> +
> +.. note::
> +       This report can be accessed when running KUnit manually by passing in the
> +       module_param ``kunit.action=list_attr``.
> +
> +Filtering
> +---------
> +
> +Users can filter tests using the ``--filter`` command line flag when running
> +tests. As an example:
> +
> +.. code-block:: bash
> +
> +       kunit.py run --filter speed=slow
> +
> +
> +You can also use the following operations on filters: "<", ">", "<=", ">=",
> +"!=", and "=". Example:
> +
> +.. code-block:: bash
> +
> +       kunit.py run --filter "speed>slow"
> +
> +This example will run all tests with speeds faster than slow. Note that the
> +characters < and > are often interpreted by the shell, so they may need to be
> +quoted or escaped, as above.
> +
> +Additionally, you can use multiple filters at once. Simply separate filters
> +using commas. Example:
> +
> +.. code-block:: bash
> +
> +       kunit.py run --filter "speed>slow, module=kunit_example_test"
> +
> +.. note::
> +       You can use this filtering feature when running KUnit manually by passing
> +       the filter as a module param: ``kunit.filter="speed>slow, speed<=normal"``.
> +
> +Filtered tests will not run or show up in the test output. You can use the
> +``--filter_action=skip`` flag to skip filtered tests instead. These tests will be
> +shown in the test output in the test but will not run. To use this feature when
> +running KUnit manually, use the module param ``kunit.filter_action=skip``.
> +
> +Rules of Filtering Procedure
> +----------------------------
> +
> +Since both suites and test cases can have attributes, there may be conflicts
> +between attributes during filtering. The process of filtering follows these
> +rules:
> +
> +- Filtering always operates at a per-test level.
> +
> +- If a test has an attribute set, then the test's value is filtered on.
> +
> +- Otherwise, the value falls back to the suite's value.
> +
> +- If neither are set, the attribute has a global "default" value, which is used.
> +
> +List of Current Attributes
> +--------------------------
> +
> +``speed``
> +
> +This attribute indicates the speed of a test's execution (how slow or fast the
> +test is).
> +
> +This attribute is saved as an enum with the following categories: "normal",
> +"slow", or "very_slow". The assumed default speed for tests is "normal". This
> +indicates that the test takes a relatively trivial amount of time (less than
> +1 second), regardless of the machine it is running on. Any test slower than
> +this could be marked as "slow" or "very_slow".
> +
> +The macro ``KUNIT_CASE_SLOW(test_name)`` can be easily used to set the speed
> +of a test case to "slow".
> +
> +``module``
> +
> +This attribute indicates the name of the module associated with the test.
> +
> +This attribute is automatically saved as a string and is printed for each suite.
> +Tests can also be filtered using this attribute.
> --
> 2.41.0.487.g6d72f3e995-goog
>

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