Refine modules.

tests/modules.rs

@@ -0,0 +1,15 @@
+use rhai::{EvalAltResult, Scope, SubScope, INT};
+
+#[test]
+#[cfg(not(feature = "no_import"))]
+fn test_sub_scope() {
+    let mut my_scope = Scope::new();
+
+    let mut sub_scope = SubScope::new();
+    sub_scope.insert("x".to_string(), (42 as INT).into());
+
+    my_scope.push_sub_scope("my_plugin", sub_scope);
+
+    let s = my_scope.find_sub_scope("my_plugin").unwrap();
+    assert_eq!(*s.get("x").unwrap().downcast_ref::<INT>().unwrap(), 42);
+}