diagnostic: add test for IPv6 minimum prefix

src/diagnostic.rs

@@ -1609,5 +1609,14 @@ mod tests {
                 .iter()
                 .any(|d| d.code == DiagnosticCode::InvalidCidrNotation)
         );
+
+        // Test edge case: IPv6 minimum prefix
+        let source_ipv6_zero = "ip6 saddr ::/0 accept";
+        let diagnostics_ipv6_zero = analyzer.validate_cidr_notation(source_ipv6_zero);
+        assert!(
+            !diagnostics_ipv6_zero
+                .iter()
+                .any(|d| d.code == DiagnosticCode::InvalidCidrNotation)
+        );
     }
 }