test: add validations for 0 target in search insert position

Author: bujosa

src/easy/search_insert_position.rs

@@ -45,6 +45,7 @@ fn test_search_insert() {
     assert_eq!(search_insert(vec![1, 3, 5, 6], 2), 1);
     assert_eq!(search_insert(vec![1, 3, 5, 6], 7), 4);
     assert_eq!(search_insert(vec![1, 3, 5, 6], 0), 0);
+    assert_eq!(search_insert(vec![1, 3], 0), 0);
     assert_eq!(search_insert(vec![1], 0), 0);
     assert_eq!(search_insert(vec![1], 2), 1);
 }