{
  "fixture": "Modbus 0x08 诊断回显",
  "cases": [
    {
      "case_id": "回送A55A",
      "kind": "正例",
      "result": {
        "subfunction": 0,
        "data_word": 42330,
        "echo_matches": true
      }
    },
    {
      "case_id": "回送零",
      "kind": "正例",
      "result": {
        "subfunction": 0,
        "data_word": 0,
        "echo_matches": true
      }
    },
    {
      "case_id": "其他子功能",
      "kind": "显式负例",
      "rejected": "仅支持子功能0000"
    },
    {
      "case_id": "数据改变",
      "kind": "显式负例",
      "rejected": "诊断数据回显不符"
    }
  ],
  "assertions_passed": 4,
  "scope": "合成输入离线演算；未接真实设备"
}