[PATCH libinput] test: add litest helper functions for creating uinput devices

[Jonas Ådahl]

On Fri, Mar 28, 2014 at 03:22:44PM +1000, Peter Hutterer wrote:
> On Thu, Mar 27, 2014 at 05:10:34PM +0100, Jonas Ådahl wrote:
> > On Thu, Mar 27, 2014 at 08:48:02AM +1000, Peter Hutterer wrote:
> > > Both functions accept a series of event types/codes tuples, terminated by -1.
> > > For the even type INPUT_PROP_MAX (an invalid type otherwise) the code is used
> > > as a property to enable.
> > > 
> > > The _abs function als takes an array of absinfo, with absinfo.value
> > > determining the axis to change. If none are given, abs axes are initialized
> > > with default settings.
> > > 
> > > Both functions abort on failure, so the caller does not need to check the
> > > return value.
> > > 
> > > Example code for creating a rel device:
> > > 
> > > struct libevdev_uinput *uinput;
> > > struct input_id id = { ... };
> > > uinput = litest_create_uinput_device("foo", &id,
> > >                                      EV_REL, REL_X,
> > >                                      EV_REL, REL_Y,
> > >                                      EV_KEY, BTN_LEFT,
> > > 				     INPUT_PROP_MAX, INPUT_PROP_BUTTONPAD,
> > >                                      -1);
> > > libevdev_uinput_write_event(uinput, EV_REL, REL_X, -1);
> > > libevdev_uinput_write_event(uinput, EV_SYN, SYN_REPORT, 0);
> > > ..
> > > libevdev_uinput_destroy(uinput);
> > 
> > The problem with this approach is that its no longer possible to use the
> > litest_touch_down, litest_touch_up etc any more. Especially for touch
> > events thats an annoyance to reimplement in the test case. We could add
> > helpers for that but then we'd have double set of helpers for every kind
> > of event we want to test.
> 
> how many devices are we talking about here. You're specifically creating a
> test device here that has one functionality that matters: a lot of slots.
> how many more devices do we expect similar to this?
> 
> IMO at least for this case it's worth writing the extra couple of lines to
> have a custom device. Once we get past the number of devices we can look
> again to see if we have some sort of common denominator.
> 
> also, litest_touch_down/up are already problematic. e.g. they don't release
> BTN_TOUCH or BTN_TOOL_FINGER because nothing refcounts the touches. they
> only solve the minimal test cases so far but the test suite needs a bit more
> work to be useful on a more general basis.
> 
> > The way I'd want to use something like this is to create a fake device,
> > possibly with some special parameters, and then use it in the same way
> > I'd use a "normal" test device. I'd rather have a way to somehow create
> > a special fake device that can be operated in the same way using the
> > same functions as a "normal" fake device.
> 
> the problem I see is with the special parameters. by the time you allow for
> all of them you end up re-implementing the current uinput API. e.g. your
> last device needed lots of slots, but what if the next device needs
> special pressure? which is exactly what I expect to be the next problem for
> the touchpad tests.
> 
> I just start at the device description files and with the patch applied they
> are now little more than static descriptions of device capabilities with the
> odd for loop to write arrays out. Maybe a solution to this is to make it
> static but better exposed that you can literally take a device, adjust a few
> nobs in the cabability bits and then create it. Would that help?

Maybe what we can do is to just have a helper that creates a
litest_device given a generic type (mouse, keyboard, touch) and a array
of parameters that libevdev_enable_event_code() takes. The helper can have
a set of basic configuration per generic type than is overwritten by the
passed parameters and then passed to libevdev_enable_event_code().

This way we could easily create a special device with many touch points,
16 generic touch devices, or a touch device with very high resoultion.

In pseudo-C, it'd be something in the line of

struct litest_device *dev;

struct input_absinfo slot_abs = {
	ABS_MT_SLOT, 0, 40, 0
};

struct litest_device_spec spec[] = {
	{ EV_KEY, BTN_LEFT, NULL },
	{ EV_KEY, BTN_RIGHT, NULL },
	{ EV_ABS, ABS_MT_SLOT, &slot_abs },
};

dev = litest_create_generic_device(LITEST_TOUCH, &spec, 3);
litest_touch_down(dev, ...);

Jonas

> 
> Cheers,
>    Peter