From patchwork Wed Sep 9 05:16:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: David Gow X-Patchwork-Id: 11764887 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1C8B5746 for ; Wed, 9 Sep 2020 05:16:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D866D21D47 for ; Wed, 9 Sep 2020 05:16:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=google.com header.i=@google.com header.b="k9HixUQw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725948AbgIIFQy (ORCPT ); Wed, 9 Sep 2020 01:16:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725807AbgIIFQu (ORCPT ); Wed, 9 Sep 2020 01:16:50 -0400 Received: from mail-qv1-xf4a.google.com (mail-qv1-xf4a.google.com [IPv6:2607:f8b0:4864:20::f4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9552DC061573 for ; Tue, 8 Sep 2020 22:16:49 -0700 (PDT) Received: by mail-qv1-xf4a.google.com with SMTP id bo17so739776qvb.2 for ; Tue, 08 Sep 2020 22:16:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:message-id:mime-version:subject:from:to:cc :content-transfer-encoding; bh=hZkaguA2IJiB+Yz+ysCYxUfYklcLU1iNq8wPCuV5FAw=; b=k9HixUQw5zlv5PBtnMXtho9JIjhYUS/sPo5INqnL78/8CsavL5dEH7CdYvwdr3qcby kTo+9kfXEj7tdWxsu9eFCsH5MqgSazUhd7v4RB5+iog3DdTrW+oaPMg59VcqMuki5gfr fVCtRrhjvRJAVnjzrCNZIzOyD8e66Qd8n8I/FAsGcz4bDueRjMnn5Utkprg3IrAiDkj9 gHUHioXuqCU0jTLKl/4uqucNP9OEoMnzuVZVkOerHaB41BppE3lzBpyFBoSZbKL8xBCg N4UrozDOd2dU4gy+/IFpA3YsBvjEMcFIQF4aIf5VbsPIRvortcRlHMOh37LJ2/Hk6bCu j7FA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:message-id:mime-version:subject:from :to:cc:content-transfer-encoding; bh=hZkaguA2IJiB+Yz+ysCYxUfYklcLU1iNq8wPCuV5FAw=; b=RT5CGiHFUBDPrsmgqGOqzXAgG3suUMKNA2p74d+J4oTKk0zqxqWJ3a1rEYGLLIQ0I6 +1l4GM4x93Jt3/JllfEp8a9gbLmuZXiPbtjxhtD+gyNxYJ0iZWDd6VRX55m1y76hvzYk zK1oMuEs7LZd5eU3mD8Oa/oXdFFpLcNXHpsDuAL7poNww05SQNa322g6co90uJv3Hybt GjdpCUcfS2r5NnAf+oISSIPc/+n/5V8fbD9U/ZPPZaFG1s4XbZ4FbanihQg8XwyDPfkH bLaUtKxAEQvpW/PntbvXI6Wc9EnGImFsEJQlLJpa0xlnShLrpRmpJmt+/1GWZwxqFtPr +RxA== X-Gm-Message-State: AOAM531/AZ8X1z9BSGXRmaR8HtBu5W/FcEDwBt/ba7Y6ghZ+px8q5reI kxivq8o2D7mjLaffjJE0Krc1qtTg2m06rA== X-Google-Smtp-Source: ABdhPJzeLN3zjFSA5UGr1FF9hLvAsmUobP1sITK9TIP9ruN/fVZ3BYJPGR1LwuSKWsDdgx0ZACpmPxNEvAaBPw== X-Received: from spirogrip.svl.corp.google.com ([2620:15c:2cb:201:42a8:f0ff:fe4d:3548]) (user=davidgow job=sendgmr) by 2002:a0c:8001:: with SMTP id 1mr2556215qva.21.1599628608615; Tue, 08 Sep 2020 22:16:48 -0700 (PDT) Date: Tue, 8 Sep 2020 22:16:31 -0700 Message-Id: <20200909051631.2960347-1-davidgow@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.28.0.526.ge36021eeef-goog Subject: [PATCH v2] Documentation: kunit: Add naming guidelines From: David Gow To: Brendan Higgins , Jonathan Corbet , Kees Cook , Alan Maguire , Randy Dunlap , "Theodore Ts'o" , Tim Bird , Marco Elver Cc: kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, David Gow Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org As discussed in [1], KUnit tests have hitherto not had a particularly consistent naming scheme. This adds documentation outlining how tests and test suites should be named, including how those names should be used in Kconfig entries and filenames. [1]: https://lore.kernel.org/linux-kselftest/202006141005.BA19A9D3@keescook/t/#u Signed-off-by: David Gow Reviewed-by: Kees Cook Reviewed-by: Brendan Higgins Reviewed-by: Marco Elver Reviewed-by: Tim Bird --- This is v2 of the KUnit test nomenclature guidelines. The guidelines have changed a bit in response to the discussion on the v1 thread which came about after plumbers. The major change is that the filename suffix is now "_test", with "_kunit" permitted where it conflicts. There are also some other exceptions carved out around existing tests, and very non-unit-like tests. Changelog: v2: - Rewrote the filename section to use "_test" as a suffix, and focus on module names, not filenames. - Add a motivating introduction, which also calls out existing tests and tests which cause problems when run automatically (long running, flaky tests) as reasons to avoid the guidelines. - Talk about including the type of test in the suite name, but only if theres an actual confict. (And update the example for this). v1: https://lore.kernel.org/linux-kselftest/20200702071416.1780522-1-davidgow@google.com/ - Fixed a bit of space/tab confusion in the index (Thanks, Randy) - Added some more examples (and some test case examples). - Added some examples of what not to call subsystems and suites. - No longer explicitly require "If unsure, put N" in Kconfig entries. - Minor formatting changes RFC: https://lore.kernel.org/linux-kselftest/20200620054944.167330-1-davidgow@google.com/T/#u - Initial version The result is a little bit weaker than the previous versions, but hopefully will let us get the areas we agree on down. -- David Documentation/dev-tools/kunit/index.rst | 1 + Documentation/dev-tools/kunit/style.rst | 207 ++++++++++++++++++++++++ 2 files changed, 208 insertions(+) create mode 100644 Documentation/dev-tools/kunit/style.rst diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst index e93606ecfb01..c234a3ab3c34 100644 --- a/Documentation/dev-tools/kunit/index.rst +++ b/Documentation/dev-tools/kunit/index.rst @@ -11,6 +11,7 @@ KUnit - Unit Testing for the Linux Kernel usage kunit-tool api/index + style faq What is KUnit? diff --git a/Documentation/dev-tools/kunit/style.rst b/Documentation/dev-tools/kunit/style.rst new file mode 100644 index 000000000000..c001ea1cd87d --- /dev/null +++ b/Documentation/dev-tools/kunit/style.rst @@ -0,0 +1,207 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================== +Test Style and Nomenclature +=========================== + +To make finding, writing, and using KUnit tests as simple as possible, it's +strongly encouraged that they are named and written according to the guidelines +below. While it's possible to write KUnit tests which do not follow these rules, +they may break some tooling, may conflict with other tests, and may not be run +automatically by testing systems. + +It's recommended that you only deviate from these guidelines when: + +1. Porting tests to KUnit which are already known with an existing name, or +2. Writing tests which would cause serious problems if automatically run (e.g., + nonderministically producing false positives or negatives, or taking an + extremely long time to run). + +Subsystems, Suites, and Tests +============================= + +In order to make tests as easy to find as possible, they're grouped into suites +and subsystems. A test suite is a group of tests which test a related area of +the kernel, and a subsystem is a set of test suites which test different parts +of the same kernel subsystem or driver. + +Subsystems +---------- + +Every test suite must belong to a subsystem. A subsystem is a collection of one +or more KUnit test suites which test the same driver or part of the kernel. A +rule of thumb is that a test subsystem should match a single kernel module. If +the code being tested can't be compiled as a module, in many cases the subsystem +should correspond to a directory in the source tree or an entry in the +MAINTAINERS file. If unsure, follow the conventions set by tests in similar +areas. + +Test subsystems should be named after the code being tested, either after the +module (wherever possible), or after the directory or files being tested. Test +subsystems should be named to avoid ambiguity where necessary. + +If a test subsystem name has multiple components, they should be separated by +underscores. *Do not* include "test" or "kunit" directly in the subsystem name +unless you are actually testing other tests or the kunit framework itself. + +Example subsystems could be: + +``ext4`` + Matches the module and filesystem name. +``apparmor`` + Matches the module name and LSM name. +``kasan`` + Common name for the tool, prominent part of the path ``mm/kasan`` +``snd_hda_codec_hdmi`` + Has several components (``snd``, ``hda``, ``codec``, ``hdmi``) separated by + underscores. Matches the module name. + +Avoid names like these: + +``linear-ranges`` + Names should use underscores, not dashes, to separate words. Prefer + ``linear_ranges``. +``qos-kunit-test`` + As well as using underscores, this name should not have "kunit-test" as a + suffix, and ``qos`` is ambiguous as a subsystem name. ``power_qos`` would be a + better name. +``pc_parallel_port`` + The corresponding module name is ``parport_pc``, so this subsystem should also + be named ``parport_pc``. + +.. note:: + The KUnit API and tools do not explicitly know about subsystems. They're + simply a way of categorising test suites and naming modules which + provides a simple, consistent way for humans to find and run tests. This + may change in the future, though. + +Suites +------ + +KUnit tests are grouped into test suites, which cover a specific area of +functionality being tested. Test suites can have shared initialisation and +shutdown code which is run for all tests in the suite. +Not all subsystems will need to be split into multiple test suites (e.g. simple drivers). + +Test suites are named after the subsystem they are part of. If a subsystem +contains several suites, the specific area under test should be appended to the +subsystem name, separated by an underscore. + +In the event that there are multiple types of test using KUnit within a +subsystem (e.g., both unit tests and integration tests), they should be put into +separate suites, with the type of test as the last element in the suite name. +Unless these tests are actually present, avoid using ``_test``, ``_unittest`` or +similar in the suite name. + +The full test suite name (including the subsystem name) should be specified as +the ``.name`` member of the ``kunit_suite`` struct, and forms the base for the +module name (see below). + +Example test suites could include: + +``ext4_inode`` + Part of the ``ext4`` subsystem, testing the ``inode`` area. +``kunit_try_catch`` + Part of the ``kunit`` implementation itself, testing the ``try_catch`` area. +``apparmor_property_entry`` + Part of the ``apparmor`` subsystem, testing the ``property_entry`` area. +``kasan`` + The ``kasan`` subsystem has only one suite, so the suite name is the same as + the subsystem name. + +Avoid names like: + +``ext4_ext4_inode`` + There's no reason to state the subsystem twice. +``property_entry`` + The suite name is ambiguous without the subsystem name. +``kasan_integration_test`` + Because there is only one suite in the ``kasan`` subsystem, the suite should + just be called ``kasan``. There's no need to redundantly add + ``integration_test``. Should a separate test suite with, for example, unit + tests be added, then that suite could be named ``kasan_unittest`` or similar. + +Test Cases +---------- + +Individual tests consist of a single function which tests a constrained +codepath, property, or function. In the test output, individual tests' results +will show up as subtests of the suite's results. + +Tests should be named after what they're testing. This is often the name of the +function being tested, with a description of the input or codepath being tested. +As tests are C functions, they should be named and written in accordance with +the kernel coding style. + +.. note:: + As tests are themselves functions, their names cannot conflict with + other C identifiers in the kernel. This may require some creative + naming. It's a good idea to make your test functions `static` to avoid + polluting the global namespace. + +Example test names include: + +``unpack_u32_with_null_name`` + Tests the ``unpack_u32`` function when a NULL name is passed in. +``test_list_splice`` + Tests the ``list_splice`` macro. It has the prefix ``test_`` to avoid a + name conflict with the macro itself. + + +Should it be necessary to refer to a test outside the context of its test suite, +the *fully-qualified* name of a test should be the suite name followed by the +test name, separated by a colon (i.e. ``suite:test``). + +Test Kconfig Entries +==================== + +Every test suite should be tied to a Kconfig entry. + +This Kconfig entry must: + +* be named ``CONFIG__KUNIT_TEST``: where is the name of the test + suite. +* be listed either alongside the config entries for the driver/subsystem being + tested, or be under [Kernel Hacking]→[Kernel Testing and Coverage] +* depend on ``CONFIG_KUNIT`` +* be visible only if ``CONFIG_KUNIT_ALL_TESTS`` is not enabled. +* have a default value of ``CONFIG_KUNIT_ALL_TESTS``. +* have a brief description of KUnit in the help text + +Unless there's a specific reason not to (e.g. the test is unable to be built as +a module), Kconfig entries for tests should be tristate. + +An example Kconfig entry: + +.. code-block:: none + + config FOO_KUNIT_TEST + tristate "KUnit test for foo" if !KUNIT_ALL_TESTS + depends on KUNIT + default KUNIT_ALL_TESTS + help + This builds unit tests for foo. + + For more information on KUnit and unit tests in general, please refer + to the KUnit documentation in Documentation/dev-tools/kunit + + If unsure, say N + + +Test File and Module Names +========================== + +KUnit tests can often be compiled as a module. These modules should be named +after the test suite, followed by ``_test``. If this is likely to conflict with +non-KUnit tests, the suffic ``_kunit`` can also be used. + +The easiest way of achieving this is to name the file containing the test suite +``_test.c`` (or, as above, ``_kunit.c``). This file should be +placed next to the code under test. + +If the suite name contains some or all of the name of the test's parent +directory, it may make sense to modify the source filename to reduce redundancy. +For example, a ``foo_firmware`` suite could be in the ``foo/firmware_test.c`` +file. + +