[test] add test for gradient with no stops

Boris Zbarsky reported a bug where having zero stops in a
gradient pattern would crash in the quartz surface. This
test checks for that case. Mozilla bug#407104.

This also crashes testing pdf; and the ps, svg surfaces
look suspicious (they reference stops[0]) but I havent
been able to test them yet.

test/Makefile.am

@@ -50,6 +50,7 @@ get-clip                        \
 get-group-target		\
 get-path-extents                \
 gradient-alpha			\
+gradient-zero-stops \
 infinite-join			\
 in-fill-empty-trapezoid		\
 invalid-matrix			\
@@ -311,6 +312,8 @@ REFERENCE_IMAGES = \
 	glyph-cache-pressure-ref.png	\
 	gradient-alpha-ref.png	\
 	gradient-alpha-rgb24-ref.png	\
+	gradient-zero-stops-ref.png	\
+	gradient-zero-stops-rgb24-ref.png	\
 	infinite-join-ref.png	\
 	leaky-dash-ps-argb32-ref.png	\
 	leaky-dash-ref.png	\

test/gradient-zero-stops.c

@@ -0,0 +1,66 @@
+/*
+ * Copyright © 2007 Brian Ewins
+ *
+ * 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: Brian Ewins <Brian.Ewins@gmail.com>
+ */
+
+#include "cairo-test.h"
+
+/* This test case is designed to exercise the following bug:
+ *
+ *      Crash when trying to paint gradient with no stops
+ *      https://bugzilla.mozilla.org/show_bug.cgi?id=407104
+ */
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "gradient-zero-stops",
+    "Verifies that gradients with no stops dont cause problems.",
+    2, 2,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_pattern_t *pat;
+    
+    pat = cairo_pattern_create_linear (0., 0., 1., 1.);
+    cairo_set_source (cr, pat);
+    cairo_paint (cr);
+    cairo_pattern_destroy (pat);
+
+    pat = cairo_pattern_create_radial (0., 0., 0., 1., 1., 1.);
+    cairo_set_source (cr, pat);
+    cairo_paint (cr);
+    cairo_pattern_destroy (pat);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}