Added a test for backtracking.

DustJS appears to not do any backtracking.

src/renderer/renderer.rs

@@ -178,7 +178,7 @@ impl<'a> DustRenderer<'a> {
     }
 }
 
-fn walk_path<'a>(
+fn new_walk_path<'a>(
     context: &'a dyn ContextElement,
     path: &Vec<&str>,
     breadcrumbs: Vec<&'a dyn ContextElement>,
@@ -192,6 +192,21 @@ fn walk_path<'a>(
     Ok(output)
 }
 
+// TODO: rename walk_path_from_single_level
+/// Attempts to walk a path from only 1 level in the context breadcrumbs
+fn walk_path<'a>(
+    context: &'a dyn ContextElement,
+    path: &Vec<&str>,
+) -> Result<&'a dyn ContextElement, RenderError<'a>> {
+    let mut output = context;
+
+    for elem in path.iter() {
+        output = output.walk(elem)?;
+    }
+
+    Ok(output)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;