[PATCH] drm/tests: Add test case for drm_rect_clip_scaled()

[nelsonbogado99 <nelosonbrizue99@gmail.com>]

From: Nelson Bogado <nelosonbrizue99@gmail.com>

To evaluate the behavior of the drm_rect_clip_scaled() helper function
with misplaced rectangles and improve the robustness and quality of it.

The new test was executed using the following command:

  $ ./tools/testing/kunit/kunit.py run --kunitconfig=drivers/gpu/drm/tests/
  [01:48:12] ================== drm_rect (10 subtests) ==================
  ...
  [01:48:12] [PASSED] drm_test_rect_clip_scaled_out_of_bounds

Signed-off-by: Nelson Bogado <nelosonbrizue99@gmail.com>
---
 drivers/gpu/drm/tests/drm_rect_test.c | 53 +++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/gpu/drm/tests/drm_rect_test.c b/drivers/gpu/drm/tests/drm_rect_test.c
index 76332cd2ead8..b3bfdd420123 100644
--- a/drivers/gpu/drm/tests/drm_rect_test.c
+++ b/drivers/gpu/drm/tests/drm_rect_test.c
@@ -209,6 +209,58 @@ static void drm_test_rect_clip_scaled_signed_vs_unsigned(struct kunit *test)
 	KUNIT_EXPECT_FALSE_MSG(test, drm_rect_visible(&src), "Source should not be visible\n");
 }
 
+static void drm_test_rect_clip_scaled_out_of_bounds(struct kunit *test)
+{
+	/* Definition of the rectangles and visible variables */
+	struct drm_rect src, dst, clip;
+	bool visible;
+
+	/*
+	 * Both rectangles are completely out of bounds, initialize the src,
+	 * dst and clip rectangles with specific coordinates and sizes.
+	 */
+	drm_rect_init(&src, -10, -10, -5, -5);
+	drm_rect_init(&dst, -20, -20, -15, -15);
+	drm_rect_init(&clip, 0, 0, 100, 100);
+
+	/* Function call drm_rect_clip_scaled to determine visibility */
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	/* Check expected results */
+	KUNIT_EXPECT_FALSE_MSG(test, visible, "Destination should not be visible\n");
+	KUNIT_EXPECT_FALSE_MSG(test, drm_rect_visible(&src), "Source should not be visible\n");
+
+	/*
+	 * Only source rectangle is out of bounds, reinitialize the src,
+	 * dst and clip rectangles with new values.
+	 */
+	drm_rect_init(&src, -10, -10, -5, -5);
+	drm_rect_init(&dst, 0, 0, 10, 10);
+	drm_rect_init(&clip, 0, 0, 100, 100);
+
+	/* Function call drm_rect_clip_scaled to determine visibility */
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	/* Check expected results */
+	KUNIT_EXPECT_TRUE_MSG(test, visible, "Destination should be visible\n\n");
+	KUNIT_EXPECT_FALSE_MSG(test, drm_rect_visible(&src), "Source should not be visible\n");
+
+	/*
+	 * Only source rectangle is out of bounds, reinitialize the src,
+	 * dst and clip rectangles with new values.
+	 */
+	drm_rect_init(&src, 0, 0, 10, 10);
+	drm_rect_init(&dst, -10, -10, -5, -5);
+	drm_rect_init(&clip, 0, 0, 100, 100);
+
+	/* Function call drm_rect_clip_scaled to determine visibility */
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	/* Check expected results */
+	KUNIT_EXPECT_FALSE_MSG(test, visible, "Destination should not be visible\n");
+	KUNIT_EXPECT_FALSE_MSG(test, drm_rect_visible(&src), "Source should not be visible\n");
+}
+
 struct drm_rect_intersect_case {
 	const char *description;
 	struct drm_rect r1, r2;
@@ -511,6 +563,7 @@ static struct kunit_case drm_rect_tests[] = {
 	KUNIT_CASE(drm_test_rect_clip_scaled_not_clipped),
 	KUNIT_CASE(drm_test_rect_clip_scaled_clipped),
 	KUNIT_CASE(drm_test_rect_clip_scaled_signed_vs_unsigned),
+	KUNIT_CASE(drm_test_rect_clip_scaled_out_of_bounds),
 	KUNIT_CASE_PARAM(drm_test_rect_intersect, drm_rect_intersect_gen_params),
 	KUNIT_CASE_PARAM(drm_test_rect_calc_hscale, drm_rect_scale_gen_params),
 	KUNIT_CASE_PARAM(drm_test_rect_calc_vscale, drm_rect_scale_gen_params),
-- 
2.40.1