[test] bc-db-reader: add default_personal_difficulty

lib/modules-lib/bc-db-reader/src/current_frame.rs

@@ -155,6 +155,14 @@ mod tests {
         assert_eq!(0, handicap(1, 50));
     }
 
+    #[test]
+    fn test_default_personal_difficulty() {
+        assert_eq!(PersonalDifficulty {
+            exclusion_factor: 1,
+            handicap: 0,
+        },PersonalDifficulty::default());
+    }
+
     #[test]
     fn test_compute_personal_difficulty_no_penality() {
         assert_eq!(