Add tests

tests/native_tests/with_decorator.hy

@@ -7,6 +7,15 @@
     (* 2 2)))
 
 
+(defn bardec [cls]
+  (setv cls.my_attr 123))
+
+(with-decorator bardec
+  (defclass cls []
+    [[my_attr 456]]))
+
+
 (defn test-decorators []
   "NATIVE: test decorators."
-  (assert (= (tfunction) 2)))
+  (assert (= (tfunction) 2))
+  (assert (= cls.my_attr 123)))