test: Add path-stroke-twice

Exercises a bug found by alois@astro.ch, whereby we inadvertently remove
a line segment when the path doubles back upon itself.

  Bug 26010 - cairo_line_to optimizes away path segments
  http://bugs.freedesktop.org/show_bug.cgi?id=26010

test/Makefile.am

@@ -757,6 +757,8 @@ REFERENCE_IMAGES = \
 	pass-through.rgb24.ref.png \
 	path-append.ps.ref.png \
 	path-append.ref.png \
+	path-stroke-twice.ref.png \
+	path-stroke-twice.ps.ref.png \
 	path-append.test-fallback.ref.png \
 	path-append.xlib-fallback.ref.png \
 	path-append.xlib.ref.png \

test/Makefile.sources

@@ -155,6 +155,7 @@ test_sources = \
 	paint-source-alpha.c				\
 	paint-with-alpha.c				\
 	path-append.c					\
+	path-stroke-twice.c				\
 	path-precision.c				\
 	pattern-get-type.c				\
 	pattern-getters.c				\

test/path-stroke-twice.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2010 Chris Wilson
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON BE LIABLE FOR ANY SPECIAL,
+ * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+ * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Author: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+/* Exercises a bug found by alois@astro.ch:
+ *   http://bugs.freedesktop.org/show_bug.cgi?id=26010
+ *   cairo_line_to optimizes away path segment
+ */
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_set_source_rgb (cr, 1, 1, 1);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_move_to (cr, 10, 10);
+    cairo_line_to (cr, 10, 20);
+    cairo_line_to (cr, 20, 30);
+    cairo_line_to (cr, 10, 20);
+    cairo_stroke (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (path_stroke_twice,
+	    "Tests stroking of a path containing a segment drawn twice",
+	    "path, stroke", /* keywords */
+	    NULL, /* requirements */
+	    40, 40,
+	    NULL, draw)