[PATCH libinput 2/7] test: Make relative pointer event test more accepting

[Jonas Ådahl]

A test cannot exactly predict the resulting motion event from a given
evdev event series without having to reimplement the acceleration
algorithm. To still be able to test that sane relative motion events are
produced, check that the length and direction of the resulting motion
event vectors are close to the same as the expected vectors.

Signed-off-by: Jonas Ådahl <jadahl at gmail.com>
---
 test/pointer.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/test/pointer.c b/test/pointer.c
index cae9f09..f47e094 100644
--- a/test/pointer.c
+++ b/test/pointer.c
@@ -27,6 +27,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <libinput.h>
+#include <math.h>
 #include <unistd.h>
 
 #include "libinput-util.h"
@@ -38,7 +39,17 @@ test_relative_event(struct litest_device *dev, int dx, int dy)
 	struct libinput *li = dev->libinput;
 	struct libinput_event *event;
 	struct libinput_event_pointer *ptrev;
-
+	double ev_dx, ev_dy;
+	double expected_dir;
+	double expected_length;
+	double actual_dir;
+	double actual_length;
+
+	/* Send two deltas, as the first one may be eaten up by an
+	 * acceleration filter. */
+	litest_event(dev, EV_REL, REL_X, dx);
+	litest_event(dev, EV_REL, REL_Y, dy);
+	litest_event(dev, EV_SYN, SYN_REPORT, 0);
 	litest_event(dev, EV_REL, REL_X, dx);
 	litest_event(dev, EV_REL, REL_Y, dy);
 	litest_event(dev, EV_SYN, SYN_REPORT, 0);
@@ -51,10 +62,25 @@ test_relative_event(struct litest_device *dev, int dx, int dy)
 
 	ptrev = libinput_event_get_pointer_event(event);
 	ck_assert(ptrev != NULL);
-	ck_assert_int_eq(libinput_event_pointer_get_dx(ptrev), li_fixed_from_int(dx));
-	ck_assert_int_eq(libinput_event_pointer_get_dy(ptrev), li_fixed_from_int(dy));
+
+	expected_length = sqrt(dx*dx + dy*dy);
+	expected_dir = atan2(dx, dy);
+
+	ev_dx = li_fixed_to_double(libinput_event_pointer_get_dx(ptrev));
+	ev_dy = li_fixed_to_double(libinput_event_pointer_get_dy(ptrev));
+	actual_length = sqrt(ev_dx*ev_dx + ev_dy*ev_dy);
+	actual_dir = atan2(ev_dx, ev_dy);
+
+	/* Check the length of the motion vector (tolerate 1.0 indifference). */
+	ck_assert(fabs(expected_length - actual_length) < 1.0);
+
+	/* Check the direction of the motion vector (tolerate 2π/4 radians
+	 * indifference). */
+	ck_assert(fabs(expected_dir - actual_dir) < M_PI_2);
 
 	libinput_event_destroy(event);
+
+	litest_drain_events(dev->libinput);
 }
 
 START_TEST(pointer_motion_relative)
-- 
1.9.1