chore: improve .dot debug API (#586)

src/utils.rs

@@ -31,11 +31,22 @@ pub fn collect_array<const N: usize, T: Debug>(arr: &[T]) -> [&T; N] {
 // Test only utils
 #[cfg(test)]
 pub(crate) mod test {
+    #[allow(unused_imports)]
+    use crate::HugrView;
+
     /// Open a browser page to render a dot string graph.
+    ///
+    /// This can be used directly on the output of `Hugr::dot_string`
     #[cfg(not(ci_run))]
-    pub(crate) fn viz_dotstr(dotstr: &str) {
+    pub(crate) fn viz_dotstr(dotstr: impl AsRef<str>) {
         let mut base: String = "https://dreampuf.github.io/GraphvizOnline/#".into();
-        base.push_str(&urlencoding::encode(dotstr));
+        base.push_str(&urlencoding::encode(dotstr.as_ref()));
         webbrowser::open(&base).unwrap();
     }
+
+    /// Open a browser page to render a HugrView's dot string graph.
+    #[cfg(not(ci_run))]
+    pub(crate) fn viz_hugr(hugr: &impl HugrView) {
+        viz_dotstr(hugr.dot_string());
+    }
 }