From f4381cffb8757d3ffba9f5710bcc6268c3d2601a Mon Sep 17 00:00:00 2001
From: ju6ge <judge@felixrichter.tech>
Date: Sun, 22 Mar 2026 15:54:53 +0100
Subject: [PATCH] test detection of dual bit errors with hemming

---
 lib-bms-protocol/src/types.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib-bms-protocol/src/types.rs b/lib-bms-protocol/src/types.rs
index df944a9..c9c325e 100644
--- a/lib-bms-protocol/src/types.rs
+++ b/lib-bms-protocol/src/types.rs
@@ -343,4 +343,14 @@ mod base_type_tests {
             assert_eq!(invalid_hemming^hc, hemming);
         }
     }
+
+    #[test]
+    fn hemming_dual_bit_error_detection() {
+        let data = 0x123456;
+        let hemming = calc_hemming(data);
+        let bit_error = 0x101;
+        let correction = check_hemming(data ^ bit_error, hemming).unwrap_err();
+        let (dc, hc) = correction.calc_correction_data();
+        assert!(check_hemming(data ^ dc, hemming ^ hc).is_err())
+    }
 }