Re: [dpdk-dev] [PATCH] guides: add a testing guide for developing tests

["Kinsella, Ray" <mdr@ashroe.eu>]

On 08/02/2021 16:52, Aaron Conole wrote:
> The DPDK testing infrastructure includes a comprehensive set of
> libraries, utilities, and CI integrations for developers to test
> their code changes.  This isn't well documented, however.
> 
> Document the basics for adding a test suite to the infrastructure
> and enabling that test suite for continuous integration platforms
> so that newer developers can understand how to develop test suites
> and test cases.
> 
> Signed-off-by: Aaron Conole <aconole@redhat.com>
> ---
> v0: Added information for TEST_SKIPPED and details about generating
>     code coverage to help with ideas for writing unit test cases.
> 
>  doc/guides/contributing/index.rst   |   1 +
>  doc/guides/contributing/testing.rst | 231 ++++++++++++++++++++++++++++
>  2 files changed, 232 insertions(+)
>  create mode 100644 doc/guides/contributing/testing.rst
> 
> diff --git a/doc/guides/contributing/index.rst b/doc/guides/contributing/index.rst
> index 2fefd91931..41909d949b 100644
> --- a/doc/guides/contributing/index.rst
> +++ b/doc/guides/contributing/index.rst
> @@ -14,6 +14,7 @@ Contributor's Guidelines
>      abi_versioning
>      documentation
>      patches
> +    testing
>      vulnerability
>      stable
>      cheatsheet
> diff --git a/doc/guides/contributing/testing.rst b/doc/guides/contributing/testing.rst
> new file mode 100644
> index 0000000000..3ade654772
> --- /dev/null
> +++ b/doc/guides/contributing/testing.rst
> @@ -0,0 +1,231 @@
> +..  SPDX-License-Identifier: BSD-3-Clause
> +    Copyright 2018 The DPDK contributors
> +
> +.. _testing_guidelines:
> +
> +DPDK Testing Guidelines
> +=======================
> +
> +This document outlines the guidelines for running and adding new
> +tests to the in-tree DPDK test suites.
> +
> +The DPDK test suite model is loosely based on the xunit model, where
> +tests are grouped into test suites, and suites are run by runners.
> +For a basic overview, see the basic Wikipedia article on xunit:
> +`xUnit - Wikipedia <https://en.wikipedia.org/wiki/XUnit>`_.
> +
> +
> +Running a test
> +--------------
> +
> +DPDK tests are run via the main test runniner, the `dpdk-test` app.

runner

> +The `dpdk-test` app is a command-line interface that facilitates
> +running various tests or test suites.
> +
> +There are two modes of operation.  The first mode is as an interactive
> +command shell that allows launching specific test suites.  This is
> +the default operating mode of `dpdk-test` and can be done by::

is the double :: intentional?

> +
> +  $ ./build/app/test/dpdk-test --dpdk-options-here
> +  EAL: Detected 4 lcore(s)
> +  EAL: Detected 1 NUMA nodes
> +  EAL: Static memory layout is selected, amount of reserved memory can be adjusted with -m or --socket-mem
> +  EAL: Multi-process socket /run/user/26934/dpdk/rte/mp_socket
> +  EAL: Selected IOVA mode 'VA'
> +  EAL: Probing VFIO support...
> +  EAL: PCI device 0000:00:1f.6 on NUMA socket -1
> +  EAL:   Invalid NUMA socket, default to 0
> +  EAL:   probe driver: 8086:15d7 net_e1000_em
> +  APP: HPET is not enabled, using TSC as default timer
> +  RTE>>
> +
> +At the prompt, simply type the name of the test suite you wish to run
> +and it will execute.
> +
> +The second form is useful for a scripting environment, and is used by
> +the DPDK meson build system.  This mode is invoked by assigning a
> +specific test suite name to the environment variable `DPDK_TEST`
> +before invoking the `dpdk-test` command, such as::
> +
> +  $ DPDK_TEST=version_autotest ./build/app/test/dpdk-test --no-huge

better to say --dpdk-options-here instead of --no-huge, as above. 

> +  EAL: Detected 4 lcore(s)
> +  EAL: Detected 1 NUMA nodes
> +  EAL: Static memory layout is selected, amount of reserved memory can be adjusted with -m or --socket-mem
> +  EAL: Multi-process socket /run/user/26934/dpdk/rte/mp_socket
> +  EAL: Selected IOVA mode 'VA'
> +  EAL: Probing VFIO support...
> +  EAL: PCI device 0000:00:1f.6 on NUMA socket -1
> +  EAL:   Invalid NUMA socket, default to 0
> +  EAL:   probe driver: 8086:15d7 net_e1000_em
> +  APP: HPET is not enabled, using TSC as default timer
> +  RTE>>version_autotest
> +  Version string: 'DPDK 20.02.0-rc0'
> +  Test OK
> +  RTE>>$
> +
> +The above shows running a specific test case.  On success, the return
> +code will be '0', otherwise it will be set to some error value (such
> +as '255').
> +
> +
> +Running all tests
> +-----------------
> +
> +In order to allow developers to quickly execute all the standard
> +internal tests without needing to remember or look up each test suite
> +name, the build system includes a standard way of executing the
> +default test suites.  After building via `ninja`, the ``meson test``
> +command will execute the standard tests and report errors.
> +
> +There are four groups of default test suites.  The first group is
> +the **fast** test suite, which is the largest group of test cases.
> +These are the bulk of the unit tests to validate functional blocks.
> +The second group is the **perf** tests.  These test suites can take
> +longer to run and do performance evaluations.  The third group is
> +the **driver** test suite, which is mostly for special hardware
> +related testing (such as `cryptodev`).  The last group are the
> +**debug** tests.  These mostly are used to dump system information.
> +
> +The suites can be selected by adding the ``--suite`` option to the
> +``meson test`` command.  Ex: ``meson test --suite fast-tests``

show some console output in this section?

> +
> +
> +Adding test suites
> +------------------
> +
> +To add a testsuite to the DPDK test application, create a new test
> +file for that suite (ex: see *app/test/test_version.c* for the
> +``version_autotest`` test suite).  There are two useful things:

There are two useful things?

> +
> +  1. REGISTER_TEST_COMMAND(command_name, function_to_execute)
> +     Registers a test command with the name `command_name` and which
> +     runs the function `function_to_execute` when `command_name` is
> +     invoked.
> +
> +  2. unit_test_suite_runner(struct unit_test_suite \*)
> +     Returns a runner for a full test suite object, which contains
> +     a test suite name, setup, teardown, and vector of unit test
> +     cases.
> +
> +Each test suite has a setup and teardown function that runs at the
> +beginning and end of the test suite execution.  Each unit test has
> +a similar function for test case setup and teardown.
> +
> +Adding test cases is controlled via the `.unit_test_cases` element

Test cases are added to the .unit_test_cases element of the 
of the unit test suite structure. 

> +of the unit test suite.  Ex:
> +
> +.. code-block:: c
> +   :linenos:
> +
> +   #include <time.h>
> +
> +   #include <rte_common.h>
> +   #include <rte_cycles.h>
> +   #include <rte_hexdump.h>
> +   #include <rte_random.h>
> +
> +   #include "test.h"
> +
> +   static int testsuite_setup(void) { return TEST_SUCCESS; }
> +   static void testsuite_teardown(void) { }
> +
> +   static int ut_setup(void) { return TEST_SUCCESS; }
> +   static void ut_teardown(void) { }
> +
> +   static int test_case_first(void) { return TEST_SUCCESS; }
> +
> +   static struct unit_test_suite example_testsuite = {
> +          .suite_name = "EXAMPLE TEST SUITE",
> +          .setup = testsuite_setup,
> +          .teardown = testsuite_teardown,
> +          .unit_test_cases = {
> +               TEST_CASE_ST(ut_setup, ut_teardown, test_case_first),
> +
> +               TEST_CASES_END(), /**< NULL terminate unit test array */
> +          },
> +   };
> +
> +   static int example_tests()
> +   {
> +       return unit_test_suite_runner(&example_testsuite);
> +   }
> +
> +   REGISTER_TEST_COMMAND(example_autotest, example_tests);
> +
> +The above code block is a small example that can be used to create a
> +complete test suite with test case.
> +
> +
> +Designing a test
> +----------------
> +
> +Test cases have multiple ways of indicating an error has occurred,
> +in order to reflect failure state back to the runner.  Using the
> +various methods of indicating errors can assist in not only validating
> +the requisite functionality is working, but also to help debug when
> +a change in environment or code has caused things to go wrong.
> +
> +The first way to indicate a generic error is by returning a test
> +result failure, using the *TEST_FAILED* error code.  This is the most
> +basic way of indicating that an error has occurred in a test routine.
> +It isn't very informative to the user, so it should really be used in
> +cases where the test has catastrophically failed.
> +
> +The preferred method of indicating an error is via the
> +`RTE_TEST_ASSERT` family of macros, which will immediately return
> +*TEST_FAILED* error condition, but will also log details about the
> +failure.  The basic form is:
> +
> +.. code-block:: c
> +
> +   RTE_TEST_ASSERT(cond, msg, ...)
> +
> +In the above macro, *cond* is the condition to evaluate to **true**.
> +Any generic condition can go here.  The *msg* parameter will be a
> +message to display if *cond* evaluates to **false**.  Some specialized
> +macros already exist.  See `lib/librte_eal/include/rte_test.h` for
> +a list of pre-build test assertions.
> +
> +Sometimes it is important to indicate that a test needs to be
> +skipped, either because the environment isn't able to support running
> +the test, or because some requisite functionality isn't availble.  The

available

> +test suite supports returning a result of `TEST_SKIPPED` during test
> +case setup, or during test case execution to indicate that the
> +preconditions of the test aren't available.  A skipped test isn't the
> +same as a failed test.  Failed tests indicate that all required
> +functionality was enabled, and the environment was correct but the
> +test failed due to some error in logic.  A skipped test indicates
> +that the test setup wasn't available to run.

Simpler to provide an example of a skipped test, than a long explanation?

> +
> +
> +Checking code coverage
> +----------------------
> +One of the best ways to help design a test case is to add a new test
> +which exercises functionality that doesn't currently have a test case.
> +The best way to find these is to run the test suite with some
> +additional code coverage reporting turned on.  

I would drop the previous sentences.
They would just confuse a reader looking to generate code coverage.

> The meson build system
> +supports generating a code coverage report via the `-Db_coverage=true`
> +option, in conjunction with a package like **lcov**, to generate an
> +HTML code coverage report.  Example::
> +
> +  $ meson covered -Db_coverage=true
> +  $ meson test -C covered --suite fast-tests
> +  $ ninja coverage-html -C covered
> +
> +The above will generate an html report in the
> +`covered/meson-logs/coveragereport/` directory that can be explored
> +for detailed code covered information.  This can be used to assist
> +in test development.
> +
> +
> +Adding a suite to the default
> +-----------------------------
> +
> +Adding to one of the default tests involves editing the appropriate
> +meson build file `app/test/meson.build` and adding the command to
> +the correct test suite class.  Once added, the new test suite will
> +be run as part of the appropriate class (fast, perf, driver, etc.).
> +
> +Some of these default test suites are run during continuous integration
> +tests, making regression checking automatic for new patches submitted
> +to the project.
>