Date:   Mon, 13 Mar 2023 15:29:24 +0200
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Matti Vaittinen <mazziesaccount@gmail.com>
Cc:     Jonathan Cameron <jic23@kernel.org>,
        Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Shreeya Patel <shreeya.patel@collabora.com>,
        Paul Gazzillo <paul@pgazz.com>,
        Dmitry Osipenko <dmitry.osipenko@collabora.com>,
        Zhigang Shi <Zhigang.Shi@liteon.com>,
        linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org
Subject: Re: [PATCH v3 2/6] iio: light: Add gain-time-scale helpers
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On Mon, Mar 13, 2023 at 03:11:52PM +0200, Matti Vaittinen wrote:
> On 3/13/23 14:40, Andy Shevchenko wrote:
> > On Sun, Mar 12, 2023 at 05:08:48PM +0000, Jonathan Cameron wrote:
> > > On Sun, 12 Mar 2023 17:06:38 +0000
> > > Jonathan Cameron <jic23@kernel.org> wrote:

...

> > > Ah. I forgot the tests that don't have a device so can't use devm.
> > 
> > Why not? I have seen, IIRC, test cases inside the kernel that fakes the device
> > for that.
> 
> I'd appreciated any pointer for such an example if you have one at hand. (I
> can do the digging if you don't though!)
> 
> I am not a fan of unit tests. They add huge amount of inertia to
> development, and in worst case, they stop people from contributing where
> improving a feature requires test code modification(s). And harder the test
> code is to understand, worse the unwanted side-effects. Also, harder the
> test code is to read, more time and effort it requires to analyze a test
> failure... Hence, I am _very_ conservative what comes to adding size of test
> code with anything that is not strictly required.
> 
> After that being said, unit tests are a great tool when carefully used - and
> I assume/hope stubbing a device for devm_ tests does not add much extra...
> But let me see if I can find an example :)

drivers/gpu/drm/tests/drm_managed_test.c ?

(somewhere underneath:

 ret = platform_driver_register(&fake_platform_driver);

which suggests... what exactly? :-)

-- 
With Best Regards,
Andy Shevchenko