Use default rust directory structure for tests

tests/method_call.rs

@@ -0,0 +1,36 @@
+extern crate rhai;
+
+use rhai::Engine;
+use rhai::RegisterFn;
+
+#[test]
+fn test_method_call() {
+    #[derive(Clone)]
+    struct TestStruct {
+        x: i64,
+    }
+
+    impl TestStruct {
+        fn update(&mut self) {
+            self.x += 1000;
+        }
+
+        fn new() -> TestStruct {
+            TestStruct { x: 1 }
+        }
+    }
+
+    let mut engine = Engine::new();
+
+    engine.register_type::<TestStruct>();
+
+    engine.register_fn("update", TestStruct::update);
+    engine.register_fn("new_ts", TestStruct::new);
+
+    if let Ok(result) = engine.eval::<TestStruct>("let x = new_ts(); x.update(); x") {
+        assert_eq!(result.x, 1001);
+    } else {
+        assert!(false);
+    }
+
+}