[librsvg: 3/7] Ensure that <transform-list> is not empty in the transform property

[Marge Bot <marge-bot src gnome org>]

commit 6e18a523c942fdb8c985b9d71f56cd5ee61d7ba3
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Aug 31 17:53:33 2021 -0500

    Ensure that <transform-list> is not empty in the transform property
    
    Whereas the SVG1.1 attribute allows transform="", the SVG2 property
    must not have an empty list of <transform-function>.
    
    Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/582>

 src/transform.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)
---
diff --git a/src/transform.rs b/src/transform.rs
index 40a7e57f..e7c493c5 100644
--- a/src/transform.rs
+++ b/src/transform.rs
@@ -109,11 +109,11 @@ fn parse_transform_prop_function_list<'i>(
     let mut v = Vec::<TransformFunction>::new();
 
     loop {
+        v.push(parse_transform_prop_function_command(parser)?);
+
         if parser.is_exhausted() {
             break;
         }
-
-        v.push(parse_transform_prop_function_command(parser)?);
     }
 
     Ok(v)
@@ -900,6 +900,15 @@ mod tests {
         );
     }
 
+    #[test]
+    fn empty_transform_property_is_error() {
+        // https://www.w3.org/TR/css-transforms-1/#transform-property
+        //
+        // <transform-list> = <transform-function>+
+        //                                        ^ one or more required
+        assert!(parse_transform_prop("").is_err());
+    }
+
     #[test]
     fn test_parse_transform_property_matrix() {
         let tp = TransformProperty::List(vec![TransformFunction::Matrix(