[librsvg/rustify-rsvg-convert] Add test for rendering individual elements

[Federico Mena Quintero <federico src gnome org>]

commit 23a58031c39c90d6b5450ae32210ba45d9172682
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Jan 27 20:01:11 2021 -0600

    Add test for rendering individual elements

 .../cmdline/601-zero-stroke-width-render-only-foo.png  | Bin 0 -> 95 bytes
 tests/fixtures/cmdline/601-zero-stroke-width.svg       |   6 ++++++
 tests/src/cmdline/rsvg_convert.rs                      |  17 +++++++++++++++++
 3 files changed, 23 insertions(+)
---
diff --git a/tests/fixtures/cmdline/601-zero-stroke-width-render-only-foo.png 
b/tests/fixtures/cmdline/601-zero-stroke-width-render-only-foo.png
new file mode 100644
index 00000000..1ed070ca
Binary files /dev/null and b/tests/fixtures/cmdline/601-zero-stroke-width-render-only-foo.png differ
diff --git a/tests/fixtures/cmdline/601-zero-stroke-width.svg 
b/tests/fixtures/cmdline/601-zero-stroke-width.svg
new file mode 100644
index 00000000..ee96d474
--- /dev/null
+++ b/tests/fixtures/cmdline/601-zero-stroke-width.svg
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg"; width="100" height="100">
+  <g id="foo">
+    <rect x="50" y="50" width="10" height="10" style="stroke-width: 0; stroke: black; fill: blue"/>
+  </g>
+</svg>
diff --git a/tests/src/cmdline/rsvg_convert.rs b/tests/src/cmdline/rsvg_convert.rs
index 8bf08fc1..664279ec 100644
--- a/tests/src/cmdline/rsvg_convert.rs
+++ b/tests/src/cmdline/rsvg_convert.rs
@@ -602,6 +602,23 @@ fn export_id_option() {
         .stdout(file::is_png().with_size(127, 127));
 }
 
+#[test]
+fn export_id_with_zero_stroke_width() {
+    // https://gitlab.gnome.org/GNOME/librsvg/-/issues/601
+    //
+    // This tests a bug that manifested itself easily with the --export-id option, but it
+    // is not a bug with the option itself.  An object with stroke_width=0 was causing
+    // an extra point at the origin to be put in the bounding box, so the final image
+    // spanned the origin to the actual visible bounds of the rendered object.
+    //
+    // We can probably test this more cleanly once we have a render tree.
+    RsvgConvert::new_with_input("tests/fixtures/cmdline/601-zero-stroke-width.svg")
+        .arg("--export-id=foo")
+        .assert()
+        .success()
+        
.stdout(file::is_png().with_contents("tests/fixtures/cmdline/601-zero-stroke-width-render-only-foo.png"));
+}
+
 #[test]
 fn export_id_short_option() {
     RsvgConvert::new_with_input("tests/fixtures/api/dpi.svg")