cleanup

tests/function.rs

@@ -230,7 +230,7 @@ fn do_test(sum: Riemann, area_target: f64) {
     {
         function.update_string("sin(x)");
         assert!(function.get_test_result().is_none());
-        assert_eq!(&function.raw_func_str, "sin(x)");
+        assert_eq!(function.func_str(), "sin(x)");
 
         function.integral = false;
         function.derivative = false;