tests: Initial test and benchmark setup

Add a unit test for wlr_box and benchmark for wlr_scene_node_at as our
first test examples, lowering the barrier for adding more tests as
suitable.

test/test_box.c

@@ -0,0 +1,149 @@
+#include <assert.h>
+#include <stddef.h>
+#include <wlr/util/box.h>
+
+static void test_box_empty(void) {
+	// NULL is empty
+	assert(wlr_box_empty(NULL));
+
+	// Zero width/height
+	struct wlr_box box = { .x = 0, .y = 0, .width = 0, .height = 10 };
+	assert(wlr_box_empty(&box));
+	box = (struct wlr_box){ .x = 0, .y = 0, .width = 10, .height = 0 };
+	assert(wlr_box_empty(&box));
+
+	// Negative width/height
+	box = (struct wlr_box){ .x = 0, .y = 0, .width = -1, .height = 10 };
+	assert(wlr_box_empty(&box));
+	box = (struct wlr_box){ .x = 0, .y = 0, .width = 10, .height = -1 };
+	assert(wlr_box_empty(&box));
+
+	// Valid box
+	box = (struct wlr_box){ .x = 0, .y = 0, .width = 10, .height = 10 };
+	assert(!wlr_box_empty(&box));
+}
+
+static void test_box_intersection(void) {
+	struct wlr_box dest;
+
+	// Overlapping
+	struct wlr_box a = { .x = 0, .y = 0, .width = 100, .height = 100 };
+	struct wlr_box b = { .x = 50, .y = 50, .width = 100, .height = 100 };
+	assert(wlr_box_intersection(&dest, &a, &b));
+	assert(dest.x == 50 && dest.y == 50 &&
+		dest.width == 50 && dest.height == 50);
+
+	// Non-overlapping
+	b = (struct wlr_box){ .x = 200, .y = 200, .width = 50, .height = 50 };
+	assert(!wlr_box_intersection(&dest, &a, &b));
+	assert(dest.width == 0 && dest.height == 0);
+
+	// Touching edges
+	b = (struct wlr_box){ .x = 100, .y = 0, .width = 50, .height = 50 };
+	assert(!wlr_box_intersection(&dest, &a, &b));
+
+	// Self-intersection
+	assert(wlr_box_intersection(&dest, &a, &a));
+	assert(dest.x == a.x && dest.y == a.y &&
+		dest.width == a.width && dest.height == a.height);
+
+	// Empty input
+	struct wlr_box empty = { .x = 0, .y = 0, .width = 0, .height = 0 };
+	assert(!wlr_box_intersection(&dest, &a, &empty));
+
+	// NULL input
+	assert(!wlr_box_intersection(&dest, &a, NULL));
+	assert(!wlr_box_intersection(&dest, NULL, &a));
+}
+
+static void test_box_intersects_box(void) {
+	// Overlapping
+	struct wlr_box a = { .x = 0, .y = 0, .width = 100, .height = 100 };
+	struct wlr_box b = { .x = 50, .y = 50, .width = 100, .height = 100 };
+	assert(wlr_box_intersects(&a, &b));
+
+	// Non-overlapping
+	b = (struct wlr_box){ .x = 200, .y = 200, .width = 50, .height = 50 };
+	assert(!wlr_box_intersects(&a, &b));
+
+	// Touching edges
+	b = (struct wlr_box){ .x = 100, .y = 0, .width = 50, .height = 50 };
+	assert(!wlr_box_intersects(&a, &b));
+
+	// Self-intersection
+	assert(wlr_box_intersects(&a, &a));
+
+	// Empty input
+	struct wlr_box empty = { .x = 0, .y = 0, .width = 0, .height = 0 };
+	assert(!wlr_box_intersects(&a, &empty));
+
+	// NULL input
+	assert(!wlr_box_intersects(&a, NULL));
+	assert(!wlr_box_intersects(NULL, &a));
+}
+
+static void test_box_contains_point(void) {
+	struct wlr_box box = { .x = 10, .y = 20, .width = 100, .height = 50 };
+
+	// Interior point
+	assert(wlr_box_contains_point(&box, 50, 40));
+
+	// Inclusive lower bound
+	assert(wlr_box_contains_point(&box, 10, 20));
+
+	// Exclusive upper bound
+	assert(!wlr_box_contains_point(&box, 110, 70));
+	assert(!wlr_box_contains_point(&box, 110, 40));
+	assert(!wlr_box_contains_point(&box, 50, 70));
+
+	// Outside
+	assert(!wlr_box_contains_point(&box, 5, 40));
+	assert(!wlr_box_contains_point(&box, 50, 15));
+
+	// Empty box
+	struct wlr_box empty = { .x = 0, .y = 0, .width = 0, .height = 0 };
+	assert(!wlr_box_contains_point(&empty, 0, 0));
+
+	// NULL
+	assert(!wlr_box_contains_point(NULL, 0, 0));
+}
+
+static void test_box_contains_box(void) {
+	struct wlr_box outer = { .x = 0, .y = 0, .width = 100, .height = 100 };
+
+	// Fully contained
+	struct wlr_box inner = { .x = 10, .y = 10, .width = 50, .height = 50 };
+	assert(wlr_box_contains_box(&outer, &inner));
+
+	// Self-containment
+	assert(wlr_box_contains_box(&outer, &outer));
+
+	// Partial overlap — not contained
+	struct wlr_box partial = { .x = 50, .y = 50, .width = 100, .height = 100 };
+	assert(!wlr_box_contains_box(&outer, &partial));
+
+	// Empty inner
+	struct wlr_box empty = { .x = 0, .y = 0, .width = 0, .height = 0 };
+	assert(!wlr_box_contains_box(&outer, &empty));
+
+	// Empty outer
+	assert(!wlr_box_contains_box(&empty, &inner));
+
+	// NULL
+	assert(!wlr_box_contains_box(&outer, NULL));
+	assert(!wlr_box_contains_box(NULL, &outer));
+}
+
+int main(void) {
+#ifdef NDEBUG
+	fprintf(stderr, "NDEBUG must be disabled for tests\n");
+	return 1;
+#endif
+
+	test_box_empty();
+	test_box_intersection();
+	test_box_intersects_box();
+	test_box_contains_point();
+	test_box_contains_box();
+	return 0;
+}