diff --git a/src/p22_generate_parentheses.rs b/src/p22_generate_parentheses.rs
index 1f44d60..b3e6968 100644
--- a/src/p22_generate_parentheses.rs
+++ b/src/p22_generate_parentheses.rs
@@ -1,5 +1,6 @@
 pub struct Solution;
 impl Solution {
+    // TODO: implement
     pub fn generate_parenthesis(n: i32) -> Vec<String> {
         
         return vec![];
@@ -12,3 +13,8 @@ fn test1() {
     actual.sort();
     assert_eq!(actual, vec!["((()))","(()())","(())()","()(())","()()()"]);
 }
+
+#[test]
+fn test2() {
+    assert_eq!(Solution::generate_parenthesis(1), vec!["()"]);
+}