tests: Add surface checks

Introduce helper routines for testing surfaces against specific
conditions.  These allow tests to validate screen captures as displaying
the correct rendering results.

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-By: Derek Foreman <derekf@osg.samsung.com>
diff --git a/tests/weston-test-client-helper.h b/tests/weston-test-client-helper.h
index 43a5aa7..2564044 100644
--- a/tests/weston-test-client-helper.h
+++ b/tests/weston-test-client-helper.h
@@ -27,6 +27,7 @@
 
 #include <assert.h>
 #include <stdbool.h>
+
 #include "weston-test-runner.h"
 #include "weston-test-client-protocol.h"
 
@@ -132,6 +133,13 @@
 	void *data;
 };
 
+struct rectangle {
+	int x;
+	int y;
+	int width;
+	int height;
+};
+
 void *
 fail_on_null(void *p);
 
@@ -190,4 +198,10 @@
 char*
 screenshot_reference_filename(const char *basename, uint32_t seq);
 
+bool
+check_surfaces_equal(const struct surface *a, const struct surface *b);
+
+bool
+check_surfaces_match_in_clip(const struct surface *a, const struct surface *b, const struct rectangle *clip);
+
 #endif