Add some tests for GdkRectangle

In particular, we're testing corner cases with empty rectangles
here.

testsuite/gdk/Makefile.am

@@ -22,6 +22,7 @@ TEST_PROGS += 				\
 	display				\
 	encoding			\
 	keysyms				\
+	rectangle			\
 	rgba				\
 	seat				\
 	visual				\

testsuite/gdk/rectangle.c

@@ -0,0 +1,82 @@
+#include <gdk/gdk.h>
+
+static void
+test_rectangle_equal (void)
+{
+  GdkRectangle a = { 0, 0, 1, 1 };
+  GdkRectangle b = { 1, 1, 2, 2 };
+  GdkRectangle c = { 0, 0, 2, 2 };
+  GdkRectangle d = { 0, 0, 1, 1 };
+  GdkRectangle e = { 0, 0, 0, 0 };
+  GdkRectangle f = { 1, 1, 0, 0 };
+
+  g_assert_true (!gdk_rectangle_equal (&a, &b));
+  g_assert_true (!gdk_rectangle_equal (&a, &c));
+  g_assert_true (!gdk_rectangle_equal (&b, &c));
+  g_assert_true ( gdk_rectangle_equal (&a, &d));
+  g_assert_true (!gdk_rectangle_equal (&e, &f));
+}
+
+static void
+test_rectangle_intersect (void)
+{
+  GdkRectangle a = { 0, 0, 10, 10 };
+  GdkRectangle b = { 5, 5, 10, 10 };
+  GdkRectangle c = { 0, 0, 0, 0 };
+  GdkRectangle d = { 5, 5, 5, 5 };
+  GdkRectangle e = { 0, 0, 10, 10 };
+  GdkRectangle f = { 20, 20, 10, 10 };
+  GdkRectangle g = { 0, 0, 0, 0 };
+  GdkRectangle h = { 10, 10, 0, 0 };
+  gboolean res;
+
+  res = gdk_rectangle_intersect (&a, &b, &c);
+  g_assert_true (res);
+  g_assert_true (gdk_rectangle_equal (&c, &d));
+
+  /* non-empty, non-intersecting rectangles */
+  res = gdk_rectangle_intersect (&e, &f, &f);
+  g_assert_cmpint (f.width, ==, 0);
+  g_assert_cmpint (f.height, ==, 0);
+
+  /* empty rectangles */
+  res = gdk_rectangle_intersect (&g, &h, NULL);
+  g_assert_true (!res);
+}
+
+static void
+test_rectangle_union (void)
+{
+  GdkRectangle a = { 0, 0, 10, 10 };
+  GdkRectangle b = { 5, 5, 10, 10 };
+  GdkRectangle c = { 0, 0, 0, 0 };
+  GdkRectangle d = { 0, 0, 15, 15 };
+  GdkRectangle e = { 0, 0, 0, 0 };
+  GdkRectangle f = { 50, 50, 0, 0 };
+  GdkRectangle g = { 0, 0, 50, 50 };
+
+  gdk_rectangle_union (&a, &b, &c);
+  g_assert_true (gdk_rectangle_equal (&c, &d));
+
+  gdk_rectangle_union (&a, &b, &b);
+  g_assert_true (gdk_rectangle_equal (&b, &d));
+
+  gdk_rectangle_union (&e, &f, &f);
+  g_assert_true (gdk_rectangle_equal (&f, &g));
+}
+
+int
+main (int argc, char *argv[])
+{
+  g_test_init (&argc, &argv, NULL);
+
+  gdk_init (NULL, NULL);
+
+  g_test_bug_base ("http://bugzilla.gnome.org/");
+
+  g_test_add_func ("/rectangle/equal", test_rectangle_equal);
+  g_test_add_func ("/rectangle/intersect", test_rectangle_intersect);
+  g_test_add_func ("/rectangle/union", test_rectangle_union);
+
+  return g_test_run ();
+}