Message-ID: <CABVgOSnOEc2AGteQNwysapxmYhNy625NeErXWpg_vvci5zC-=w@mail.gmail.com>
Date: Sat, 3 Feb 2024 14:49:52 +0800
From: David Gow <davidgow@...gle.com>
To: Rae Moar <rmoar@...gle.com>
Cc: frowand.list@...il.com, keescook@...omium.org, Tim.Bird@...y.com, 
	shuah@...nel.org, brendanhiggins@...gle.com, dlatypov@...gle.com, 
	tytso@...gle.com, gustavo.padovan@...labora.com, 
	ricardo.canuelo@...labora.com, guillaume.tucker@...labora.com, corbet@....net, 
	kernelci@...ts.linux.dev, linux-kselftest@...r.kernel.org, 
	kunit-dev@...glegroups.com, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [KTAP V2 PATCH v2] ktap_v2: add test metadata

On Sat, 27 Jan 2024 at 06:15, Rae Moar <rmoar@...gle.com> wrote:
>
> Add specification for test metadata to the KTAP v2 spec.
>
> KTAP v1 only specifies the output format of very basic test information:
> test result and test name. Any additional test information either gets
> added to general diagnostic data or is not included in the output at all.
>
> The purpose of KTAP metadata is to create a framework to include and
> easily identify additional important test information in KTAP.
>
> KTAP metadata could include any test information that is pertinent for
> user interaction before or after the running of the test. For example,
> the test file path or the test speed.
>
> Since this includes a large variety of information, this specification
> will recognize notable types of KTAP metadata to ensure consistent format
> across test frameworks. See the full list of types in the specification.
>
> Example of KTAP Metadata:
>
>  KTAP version 2
>  # ktap_test: main
>  # ktap_arch: uml
>  1..1
>      KTAP version 2
>      # ktap_test: suite_1
>      # ktap_subsystem: example
>      # ktap_test_file: lib/test.c
>      1..2
>      ok 1 test_1
>      # ktap_test: test_2
>      # ktap_speed: very_slow
>      # custom_is_flaky: true
>      ok 2 test_2
>  ok 1 test_suite

This 'test_suite' name doesn't match the 'suite_1' name above.

It also could be clearer that it's supposed to match 'suite_1', not
'main', due to the indentation difference. Maybe we should add an
explicit note pointing that out?

>
> The changes to the KTAP specification outline the format, location, and
> different types of metadata.
>
> Here is a link to a version of the KUnit parser that is able to parse test
> metadata lines for KTAP version 2. Note this includes test metadata
> lines for the main level of KTAP.
>
> Link: https://kunit-review.googlesource.com/c/linux/+/5889

I tested this, and it works well. I think there's a couple of changes
we'd want for a more useful set of KUnit parser changes (namely the
option to support non ktap_ prefixes, as well as an actual way of
using this data), but I'll leave those for a future review of that
patch -- it's not relevant to this spec.

>
> Signed-off-by: Rae Moar <rmoar@...gle.com>
> ---

I like this: it covers all of the requirements we have in KUnit, as
well as a few things we'd like to add.

Is there anything obviously missing for this to work with other
usecases? Are there any other examples of metadata people want to
capture?

For me, this is
Reviewed-by: David Gow <davidgow@...gle.com>

>  Documentation/dev-tools/ktap.rst | 163 ++++++++++++++++++++++++++++++-
>  1 file changed, 159 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/dev-tools/ktap.rst b/Documentation/dev-tools/ktap.rst
> index ff77f4aaa6ef..4480eaf5bbc3 100644
> --- a/Documentation/dev-tools/ktap.rst
> +++ b/Documentation/dev-tools/ktap.rst
> @@ -17,19 +17,20 @@ KTAP test results describe a series of tests (which may be nested: i.e., test
>  can have subtests), each of which can contain both diagnostic data -- e.g., log
>  lines -- and a final result. The test structure and results are
>  machine-readable, whereas the diagnostic data is unstructured and is there to
> -aid human debugging.
> +aid human debugging. One exception to this is test metadata lines - a type
> +of diagnostic lines. Test metadata is used to identify important supplemental
> +test information and can be machine-readable.
>
>  KTAP output is built from four different types of lines:
>  - Version lines
>  - Plan lines
>  - Test case result lines
> -- Diagnostic lines
> +- Diagnostic lines (including test metadata)
>
>  In general, valid KTAP output should also form valid TAP output, but some
>  information, in particular nested test results, may be lost. Also note that
>  there is a stagnant draft specification for TAP14, KTAP diverges from this in
> -a couple of places (notably the "Subtest" header), which are described where
> -relevant later in this document.
> +a couple of places, which are described where relevant later in this document.
>
>  Version lines
>  -------------
> @@ -166,6 +167,154 @@ even if they do not start with a "#": this is to capture any other useful
>  kernel output which may help debug the test. It is nevertheless recommended
>  that tests always prefix any diagnostic output they have with a "#" character.
>
> +KTAP metadata lines
> +-------------------
> +
> +KTAP metadata lines are a subset of diagnostic lines that are used to include
> +and easily identify important supplemental test information in KTAP.
> +
> +.. code-block:: none
> +
> +       # <prefix>_<metadata type>: <metadata value>
> +
> +The <prefix> indicates where to find the specification for the type of
> +metadata. The metadata types listed below use the prefix "ktap" (See Types of
> +KTAP Metadata).
> +
> +Types that are instead specified by an individual test framework use the
> +framework name as the prefix. For example, a metadata type documented by the
> +kselftest specification would use the prefix "kselftest". Any metadata type
> +that is not listed in a specification must use the prefix "custom". Note the
> +prefix must not include spaces or the characters ":" or "_".

We should probably be more explicit about what counts as a
'specification' here, and hence whether a new prefix or 'custom'
should be used.

I'm tempted to be inspired by the OpenGL extension mechanism and say
that new prefixes must be 'registered' before they can be used, where
'registration' consists of submitting a patch to this document linking
to the specification.

> +The format of <metadata type> and <value> varies based on the type. See the
> +individual specification. For "custom" types the <metadata type> can be any
> +string excluding ":", spaces, or newline characters and the <value> can be any
> +string.
> +
> +**Location:**
> +
> +The first KTAP metadata entry for a test must be "# ktap_test: <test name>",
> +which acts as a header to associate metadata with the correct test.
> +
> +For test cases, the location of the metadata is between the prior test result
> +line and the current test result line. For test suites, the location of the
> +metadata is between the suite's version line and test plan line. See the
> +example below.
> +
> +KTAP metadata for a test does not need to be contiguous. For example, a kernel
> +warning or other diagnostic output could interrupt metadata lines. However, it
> +is recommended to keep a test's metadata lines together when possible, as this
> +improves readability.

Should we give an example of this? e.g. ktap_duration will need to be
output after the test has completed, but ktap_test must be output
before any log lines. (And most of the others probably prefer to be at
the beginning.)

I think this is the most complicated point from a parsing point of
view, so we should probably draw more attention to it.

> +
> +**Here is an example of using KTAP metadata:**
> +
> +::
> +
> +        KTAP version 2
> +        # ktap_test: main
> +        # ktap_arch: uml
> +        1..1
> +          KTAP version 2
> +          # ktap_test: suite_1
> +          # ktap_subsystem: example
> +          # ktap_test_file: lib/test.c
> +          1..2
> +          ok 1 test_1
> +          # ktap_test: test_2
> +          # ktap_speed: very_slow
> +          # custom_is_flaky: true
> +          ok 2 test_2
> +        # suite_1 passed
> +        ok 1 suite_1

Would it be clearer to have some examples which have other,
non-metadata diagnostic lines here, so we can see how they interact?

> +
> +In this example, the tests are running on UML. The test suite "suite_1" is part
> +of the subsystem "example" and belongs to the file "lib/example_test.c". It has
> +two subtests, "test_1" and "test_2". The subtest "test_2" has a speed of
> +"very_slow" and has been marked with a custom KTAP metadata type called
> +"custom_is_flaky" with the value of "true".
> +
> +**Types of KTAP Metadata:**
> +
> +This is the current list of KTAP metadata types recognized in this
> +specification. Note that all of these metadata types are optional (except for
> +ktap_test as the KTAP metadata header).
> +
> +- ``ktap_test``: Name of test (used as header of KTAP metadata). This should
> +  match the test name printed in the test result line: "ok 1 [test_name]".
> +
> +- ``ktap_module``: Name of the module containing the test
> +
> +- ``ktap_subsystem``: Name of the subsystem being tested
> +
> +- ``ktap_start_time``: Time tests started in ISO8601 format
> +
> +  - Example: "# ktap_start_time: 2024-01-09T13:09:01.990000+00:00"
> +
> +- ``ktap_duration``: Time taken (in seconds) to execute the test
> +
> +  - Example: "ktap_duration: 10.154s"
> +
> +- ``ktap_speed``: Category of how fast test runs: "normal", "slow", or
> +  "very_slow"
> +
> +- ``ktap_test_file``: Path to source file containing the test. This metadata
> +  line can be repeated if the test is spread across multiple files.
> +
> +  - Example: "# ktap_test_file: lib/test.c"
> +
> +- ``ktap_generated_file``: Description of and path to file generated during
> +  test execution. This could be a core dump, generated filesystem image, some
> +  form of visual output (for graphics drivers), etc. This metadata line can be
> +  repeated to attach multiple files to the test.
> +
> +  - Example: "# ktap_generated_file: Core dump: /var/lib/systemd/coredump/hello.core"
> +
> +- ``ktap_log_file``: Path to file containing kernel log test output
> +
> +  - Example: "# ktap_log_file: /sys/kernel/debugfs/kunit/example/results"

When should we use something generic like 'ktap_generated_file',
versus something more specific, like 'ktap_log_file'?

> +
> +- ``ktap_error_file``: Path to file containing context for test failure or
> +  error. This could include the difference between optimal test output and
> +  actual test output.
> +
> +  - Example: "# ktap_error_file: fs/results/example.out.bad"
> +
> +- ``ktap_results_url``: Link to webpage describing this test run and its
> +  results
> +
> +  - Example: "# ktap_results_url: https://kcidb.kernelci.org/hello"
> +
> +- ``ktap_arch``: Architecture used during test run
> +
> +  - Example: "# ktap_arch: x86_64"
> +
> +- ``ktap_compiler``: Compiler used during test run
> +
> +  - Example: "# ktap_compiler: gcc (GCC) 10.1.1 20200507 (Red Hat 10.1.1-1)"
> +
> +- ``ktap_respository_url``: Link to git repository of the checked out code.
> +
> +  - Example: "# ktap_respository_url: https://github.com/torvalds/linux.git"
> +
> +- ``ktap_git_branch``: Name of git branch of checked out code
> +
> +  - Example: "# ktap_git_branch: kselftest/kunit"
> +
> +- ``ktap_kernel_version``: Version of Linux Kernel being used during test run
> +
> +  - Example: "# ktap_kernel_version: 6.7-rc1"
> +
> +- ``ktap_commit_hash``: The full git commit hash of the checked out base code.
> +
> +  - Example: "# ktap_commit_hash: 064725faf8ec2e6e36d51e22d3b86d2707f0f47f"
> +
> +**Other Metadata Types:**
> +
> +There can also be KTAP metadata that is not included in the recognized list
> +above. This metadata must be prefixed with the test framework, ie. "kselftest",
> +or with the prefix "custom". For example, "# custom_batch: 20".
> +
>  Unknown lines
>  -------------
>
> @@ -206,6 +355,7 @@ An example of a test with two nested subtests:
>         KTAP version 2
>         1..1
>           KTAP version 2
> +         # ktap_test: example
>           1..2
>           ok 1 test_1
>           not ok 2 test_2
> @@ -219,6 +369,7 @@ An example format with multiple levels of nested testing:
>         KTAP version 2
>         1..2
>           KTAP version 2
> +         # ktap_test: example_test_1
>           1..2
>             KTAP version 2
>             1..2
> @@ -254,6 +405,7 @@ Example KTAP output
>         KTAP version 2
>         1..1
>           KTAP version 2
> +         # ktap_test: main_test
>           1..3
>             KTAP version 2
>             1..1
> @@ -261,11 +413,14 @@ Example KTAP output
>             ok 1 test_1
>           ok 1 example_test_1
>             KTAP version 2
> +        # ktap_test: example_test_2
> +        # ktap_speed: slow
>             1..2
>             ok 1 test_1 # SKIP test_1 skipped
>             ok 2 test_2
>           ok 2 example_test_2
>             KTAP version 2
> +           # ktap_test: example_test_3
>             1..3
>             ok 1 test_1
>             # test_2: FAIL
>
> base-commit: 906f02e42adfbd5ae70d328ee71656ecb602aaf5
> --
> 2.43.0.429.g432eaa2c6b-goog
>

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