moved mod test to top of file

src/main.rs

@@ -2,6 +2,9 @@ use num_traits::Float;
 
 mod parser;
 
+#[cfg(test)]
+mod test;
+
 /*
  * NOTES
  * - each alternative should appear only once in a tree. need to figure out a
@@ -83,6 +86,3 @@ impl<T: Eq, U: Float> Tree<T, U> {
 fn main() {
   unimplemented!();
 }
-
-#[cfg(test)]
-mod test;