test: Add white-in-noop

Exercise an incorrect optimization in cairo-surface.c. It replaces
with a noop any region-based fill with solid white source and an IN
operator.

test/Makefile.sources

@@ -293,6 +293,7 @@ test_sources = \
 	user-font-mask.c				\
 	user-font-proxy.c				\
 	user-font-rescale.c				\
+	white-in-noop.c					\
 	xcomposite-projection.c				\
 	xlib-expose-event.c 				\
 	zero-alpha.c					\

test/white-in-noop.c

@@ -0,0 +1,52 @@
+/* -*- Mode: c; c-basic-offset: 4; indent-tabs-mode: t; tab-width: 8; -*- */
+/*
+ * Copyright 2011 Andrea Canciani
+ *
+ * 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: Andrea Canciani <ranma42@gmail.com>
+ */
+
+#include "cairo-test.h"
+
+#define HEIGHT 4
+#define WIDTH 4
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_paint (cr);
+
+    cairo_set_operator (cr, CAIRO_OPERATOR_IN);
+
+    cairo_set_source_rgb (cr, 1, 1, 1);
+    cairo_paint (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (white_in_noop,
+	    "Test an invalid optimization of the IN operator with white sources",
+	    "operator", /* keywords */
+	    NULL, /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, draw)