Add a test case that asserts on xcb

Signed-off-by: Uli Schlachter <psychon@znc.in>

test/Makefile.sources

@@ -299,6 +299,7 @@ test_sources = \
 	user-font-rescale.c				\
 	white-in-noop.c					\
 	xcb-stress-cache.c				\
+	xcb-snapshot-assert.c				\
 	xcomposite-projection.c				\
 	xlib-expose-event.c 				\
 	zero-alpha.c					\

test/xcb-snapshot-assert.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright © 2011 Uli Schlachter
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Author: Uli Schlachter <psychon@znc.in>
+ */
+
+#include "cairo.h"
+#include "cairo-test.h"
+
+static cairo_surface_t *
+create_image (int width, int height)
+{
+    cairo_surface_t *surface;
+    cairo_t *cr;
+
+    surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);
+    /* Paint something random to the image */
+    cr = cairo_create (surface);
+    cairo_set_source_rgb (cr, 0, 1, 1);
+    cairo_paint (cr);
+    cairo_destroy (cr);
+
+    return surface;
+}
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    /* Image has to have same geometry as xcb surface to be added as a snapshot */
+    cairo_set_source_surface (cr, create_image (width, height), 0, 0);
+
+    /* This attaches the tested xcb surface as a snapshot */
+    cairo_paint (cr);
+
+    /* Now cairo is modifying a snapshot which fails an
+     * assert in _cairo_surface_begin_modification */
+    cairo_paint (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (xcb_snapshot_assert,
+	    "Test a wrong _cairo_surface_attach_snapshot call",
+	    "xcb", /* keywords */
+	    NULL, /* requirements */
+	    2, 2,
+	    NULL, draw)