[gegl] add test for serialization of linear keyframed animation

[Øyvind Kolås <ok src gnome org>]

commit cd2aa560b8bee34cc1a8fa94596bc5d94dd34547
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Jul 6 21:09:32 2017 +0200

    add test for serialization of linear keyframed animation

 tests/simple/test-serialize.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/tests/simple/test-serialize.c b/tests/simple/test-serialize.c
index 5047f7a..df39941 100644
--- a/tests/simple/test-serialize.c
+++ b/tests/simple/test-serialize.c
@@ -33,6 +33,15 @@ TestCase tests[] = {
      "gegl:invert-linear",
      ""},
 
+    {"threshold value=0.1",
+     "gegl:threshold value=0.10000000000000001",
+     ""},
+
+
+    {"threshold value={ 0=0.1 2=0.33 }",
+     "gegl:threshold value={  0.000000=0.100000  2.000000=0.330000  } ",
+     ""},
+  
     {"invert a=b",
      "gegl:invert-linear",
      "gegl:invert has no a property."},