Fix bug in export_graph. Don't query the value for the root key.

src/lib.rs

@@ -269,6 +269,11 @@ impl DiagnosticGraph {
         let mut statuses = Vec::<DiagnosticStatus>::new();
 
         for key in keys_in_order.iter() {
+            if *key == self.root() {
+                // The root key will always be the first one through this
+                // loop.
+                continue;
+            }
             let status_at_key = self.value_of(&key)?;
             statuses.push(status_at_key.copy_with_new_name(self.full_name_from_key(&key)?));
         }
@@ -428,4 +433,29 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn export_graph() -> Result<()> {
+        let statuses = vec![
+            make_a_status_with_name_and_level("/a", DiagnosticLevel::UNSET),
+            make_a_status_with_name_and_level("/a/b/c", DiagnosticLevel::OK),
+            make_a_status_with_name_and_level("/a/b", DiagnosticLevel::UNSET),
+            make_a_status_with_name_and_level("/a/d", DiagnosticLevel::UNSET),
+        ];
+        let mut graph = DiagnosticGraph::new();
+        graph.add_status_vec(&statuses)?;
+
+        let exported = graph.export_graph()?;
+
+        assert!(exported.len() == 4);
+        // Searching doen the b tree first would also be
+        // technically correct, but this is the order the implementation
+        // is currently going with.
+        assert!(exported[0].name() == "/a");
+        assert!(exported[1].name() == "/a/d");
+        assert!(exported[2].name() == "/a/b");
+        assert!(exported[3].name() == "/a/b/c");
+
+        Ok(())
+    }
 }