Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:126131
Message-ID: <7228b901-a6a9-4aa9-8425-5ad51f66a853@gmx.de>
Date: Mon, 16 Dec 2024 21:05:28 +0100
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PHP-DEV] C Unit testing and mocking
Content-Language: de-DE
To: Jakub Zelenka <bukka@php.net>,
 PHP internals list <internals@lists.php.net>
References: <CAEKnhAEFJKPWWL0EKu_JBPgwBEe+Pk3GDzR7HQm3J-g7=Wk0BA@mail.gmail.com>
In-Reply-To: <CAEKnhAEFJKPWWL0EKu_JBPgwBEe+Pk3GDzR7HQm3J-g7=Wk0BA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
UI-OutboundReport: notjunk:1;M01:P0:mhtXuG90k1M=;T45EyUtWhVWX/MM3jyR8U8ajR6i
 /CHRiZzHVpkWREyhFYP7XkleiIJBkuNojtInh5vxNxViC6xtuZYt7hiSfXQFj2brRBnMkWKZX
 3XYh5IK0cdiq6nqyS5fOrZJFjRwVcQJAXZi0JErkY6pADmhM6/SrJe+2tJFcpaQm+WDLL72zM
 4NZfln5k1cbPyFA2Ffv+c17oPqCU2aStnHuf7gNdfqq7+MqOIjZbS1vpBL5fH2jAbVeLnV0LE
 PLa72ZEBgizTUJM+KMuYAfTMEnKo/hleOE64vFWBTxEtoq7HR3OfjTtWE3fpKOr4xZJjeqB8O
 zCgM2pBv1luDaAi+fFPGFV8LewD71XXlC3vcMl/40MW7yKpI2Y8wtXRLZ1us+eJpEFtjJLOfn
 MWkY6eGEkUg1sVUZ8rZC+IC7pROcc71elTSLAxQWhuKvgc8W20nBOiSfaofq5l5ShXnd+jmZp
 +l/y+9Qk48opf2PaWFhQSiOZ35spAMGgXQKKs8//b0oLfJxiuVzlJZt0/FZkk9h6eUoE+rv2L
 3MxE+brXpN/k98jKjtwTJinKzcfU+vFzOZkDDgRS1OPDSgGoE/FFzV56rmeVBsNXyppwGvoLk
 GmMxUHW7NKGSJJoP1zan3/sG8ralVO3pM26ktX3B/bCJnRGJlqp1YToJnnFcDhCVeYtE6AsgH
 eBHY2vUn1JrdzqFbF+hY6I4h0Ac04wjt+noVgd5OcHu+BSsrYhgTFjOQYuvnMrBLof54rZxs3
 /Dy4k4fL36gHFvvCWCoqXZ5raqDzTlPSalG1JBSJ5ocIQiv9cD3lDJoNfR/ON6Ry2bOSUiWYQ
 CoYLti6wNzZXM71WtKUpJkC4Wh1H9wiy4u9jNZ0Te7NZSg1cAtGwZFsls2g+Q1cVCboHTvgZG
 IUokiqB0Al0mpSVcUpUK8wE2geDhb+DPfEd1+qCypBhu+C0hUYY6tOpUgA2nofIvXyXcP2u3z
 DGH8Mhn9PBSFTNv/wOeRmdeDLCzVDihW0xvk5NqIEG9f9D9zAsVC4fC5BdjUset5j8e9TS7fO
 WeLmKKYlbl2obbVSMOR4iayxNpautU3yCBldteJRKCPlQU7AAKNPNa1zcbtbwHhpmWE+XX4Rm
 +3phXg82SEov4qxfbxodCLJ2DPm1MgEkC9yt49Oh/XwTsJxSuB3dR58oV59GIegFl9n8b68SY
 =
From: cmbecker69@gmx.de ("Christoph M. Becker")

On 16.12.2024 at 14:18, Jakub Zelenka wrote:

> I have been looking into how to test some cases where integration tests are
> very difficult or even impossible to create for. Those are often found in
> networking related and system specific code code (network.c, streams, FPM
> and more). I was recently fixing one such bug and decided to give a try
> which resulted in this PR: https://github.com/php/php-src/pull/16987 .

It makes sense to me to have some unit tests for code which is otherwise
hard or even impossible to test via integration tests.

> There was a suggestion of RFC but that might be a bit too much as it's just
> an internal change / addition. But certainly some overview on internals
> should be done so writing this instead.

I'm fine with not going through the RFC process, although the policy[1]
police might come after us. :)

> I decided to use cmocka in that PR because I had some experience with that.
> It's quite small and still very powerful and allow vast mocking options.
> It's a bit manual but it gives a bigger control over the mock. It relies on
> --wrap linking option that replaces original functions with wraps. This is
> however available only on Linux (or maybe some other Unix variants) but
> doesn't work on MacOS or Windows. The developers that want to use it on
> those platforms would need to use some Linux Virtualisation option (e.g.
> Docker).

Especially on Windows, where we have different code paths, and sometimes
even completely different code, it would be great to also have these
unit tests.  Given that link.exe supports /alternatename, a bit of
additional macro magic might do the trick[2].  I'll try to have a stab
at this soon.

> I did also some research into the other mocking libraries in C.

Thank you!  I barely have any experience with unit testing in C (only
one time, long ago, wrote part of unit test for timelib which is using
Cpputest), but from a cursory glance cmocka appears to be suitable for
our purposes.

> In terms of CI. It has got its own build which is very simple and it tests
> just specific parts so we could just limit it to run only for changed files
> which might be quite convenient.

If the tests won't take long, in my opinion we could run them for every
push.  Or at least in nightly (plus when relevant files changed), to
avoid that the suite doesn't run for a long time (possibly weeks), and
then suddenly is broken for external reasons.

[1] <https://github.com/php/policies/blob/main/third-party-code.rst>
[2]
<https://stackoverflow.com/questions/33790425/visual-studio-c-linker-wrap-option>

Christoph