Fix test_eval.

tests/eval.rs

@@ -3,6 +3,23 @@ use rhai::{Engine, EvalAltResult, Scope, INT};
 #[test]
 fn test_eval() -> Result<(), EvalAltResult> {
     let mut engine = Engine::new();
+
+    assert_eq!(
+        engine.eval::<INT>(
+            r#"
+                eval("40 + 2")
+    "#
+        )?,
+        42
+    );
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_function"))]
+fn test_eval_function() -> Result<(), EvalAltResult> {
+    let mut engine = Engine::new();
     let mut scope = Scope::new();
 
     assert_eq!(
@@ -43,6 +60,7 @@ fn test_eval() -> Result<(), EvalAltResult> {
 }
 
 #[test]
+#[cfg(not(feature = "no_function"))]
 fn test_eval_override() -> Result<(), EvalAltResult> {
     let mut engine = Engine::new();