Re: [PATCH v15 00/18] kunit: introduce KUnit, the Linux kernel unit testing framework

[shuah <shuah@kernel.org>]

On 8/23/19 7:34 PM, Brendan Higgins wrote:
> ## TL;DR
> 
> This revision addresses comments from Shuah by fixing a couple
> checkpatch warnings and fixing some comment readability issues. No API
> or major structual changes have been made since v13.
> 
> ## Background
> 
> This patch set proposes KUnit, a lightweight unit testing and mocking
> framework for the Linux kernel.
> 
> Unlike Autotest and kselftest, KUnit is a true unit testing framework;
> it does not require installing the kernel on a test machine or in a VM
> (however, KUnit still allows you to run tests on test machines or in VMs
> if you want[1]) and does not require tests to be written in userspace
> running on a host kernel. Additionally, KUnit is fast: From invocation
> to completion KUnit can run several dozen tests in about a second.
> Currently, the entire KUnit test suite for KUnit runs in under a second
> from the initial invocation (build time excluded).
> 
> KUnit is heavily inspired by JUnit, Python's unittest.mock, and
> Googletest/Googlemock for C++. KUnit provides facilities for defining
> unit test cases, grouping related test cases into test suites, providing
> common infrastructure for running tests, mocking, spying, and much more.
> 
> ### What's so special about unit testing?
> 
> A unit test is supposed to test a single unit of code in isolation,
> hence the name. There should be no dependencies outside the control of
> the test; this means no external dependencies, which makes tests orders
> of magnitudes faster. Likewise, since there are no external dependencies,
> there are no hoops to jump through to run the tests. Additionally, this
> makes unit tests deterministic: a failing unit test always indicates a
> problem. Finally, because unit tests necessarily have finer granularity,
> they are able to test all code paths easily solving the classic problem
> of difficulty in exercising error handling code.
> 
> ### Is KUnit trying to replace other testing frameworks for the kernel?
> 
> No. Most existing tests for the Linux kernel are end-to-end tests, which
> have their place. A well tested system has lots of unit tests, a
> reasonable number of integration tests, and some end-to-end tests. KUnit
> is just trying to address the unit test space which is currently not
> being addressed.
> 
> ### More information on KUnit
> 
> There is a bunch of documentation near the end of this patch set that
> describes how to use KUnit and best practices for writing unit tests.
> For convenience I am hosting the compiled docs here[2].
> 
> Additionally for convenience, I have applied these patches to a
> branch[3]. The repo may be cloned with:
> git clone https://kunit.googlesource.com/linux
> This patchset is on the kunit/rfc/v5.3/v15 branch.
> 
> ## Changes Since Last Version
> 
> - Moved comment from inline in macro to kernel-doc to address checkpatch
>    warning.
> - Demoted BUG() to WARN_ON.
> - Formatted some kernel-doc comments to make them more readible.
> 
> [1] https://google.github.io/kunit-docs/third_party/kernel/docs/usage.html#kunit-on-non-uml-architectures
> [2] https://google.github.io/kunit-docs/third_party/kernel/docs/
> [3] https://kunit.googlesource.com/linux/+/kunit/rfc/v5.3/v15
> 

Hi Brendan,

Thanks for doing this work.

Thanks for accommodating my request to improve the document/comment
blocks in patch 01 and removing BUG() from patch 09. The comment block
reads well now.

Applied the series to linux-kselftest next for 5.4-rc1.

thanks,
-- Shuah