[gtk/path-stroke: 19/27] Add a test for tangents of degenerate curves

[Matthias Clasen <matthiasc src gnome org>]

commit 723809fbff3d45abf1aaeaa6bca950441018c91e
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Dec 20 11:19:43 2020 -0500

    Add a test for tangents of degenerate curves
    
    The stroker relies on these to work.

 testsuite/gsk/curve-special-cases.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)
---
diff --git a/testsuite/gsk/curve-special-cases.c b/testsuite/gsk/curve-special-cases.c
index aac4976573..dae8adbd2a 100644
--- a/testsuite/gsk/curve-special-cases.c
+++ b/testsuite/gsk/curve-special-cases.c
@@ -87,7 +87,6 @@ test_curve_tangents (void)
   gsk_curve_get_end_tangent (&c, &t);
   g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
 
-
   graphene_point_init (&p[0], 0, 0);
   graphene_point_init (&p[1], 0, 100);
   gsk_curve_init (&c, gsk_pathop_encode (GSK_PATH_LINE, p));
@@ -120,6 +119,36 @@ test_curve_tangents (void)
   g_assert_true (graphene_vec2_near (&t, graphene_vec2_y_axis (), 0.0001));
 }
 
+static void
+test_curve_degenerate_tangents (void)
+{
+  GskCurve c;
+  graphene_point_t p[4];
+  graphene_vec2_t t;
+
+  graphene_point_init (&p[0], 0, 0);
+  graphene_point_init (&p[1], 0, 0);
+  graphene_point_init (&p[2], 100, 0);
+  graphene_point_init (&p[3], 100, 0);
+  gsk_curve_init (&c, gsk_pathop_encode (GSK_PATH_CURVE, p));
+
+  gsk_curve_get_start_tangent (&c, &t);
+  g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
+  gsk_curve_get_end_tangent (&c, &t);
+  g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
+
+  graphene_point_init (&p[0], 0, 0);
+  graphene_point_init (&p[1], 50, 0);
+  graphene_point_init (&p[2], 50, 0);
+  graphene_point_init (&p[3], 100, 0);
+  gsk_curve_init (&c, gsk_pathop_encode (GSK_PATH_CURVE, p));
+
+  gsk_curve_get_start_tangent (&c, &t);
+  g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
+  gsk_curve_get_end_tangent (&c, &t);
+  g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -128,6 +157,7 @@ main (int   argc,
 
   g_test_add_func ("/curve/special/conic-segment", test_conic_segment);
   g_test_add_func ("/curve/special/tangents", test_curve_tangents);
+  g_test_add_func ("/curve/special/degenerate-tangents", test_curve_degenerate_tangents);
 
   return g_test_run ();
 }