{
  "name": "invalid/dollar-key",
  "why": "Global Constraints: keys starting with $ are forbidden ($row is reserved)",
  "rules": {
    "columns": [
      {
        "key": "$row"
      }
    ]
  },
  "rows": [
    {
      "v": "x"
    }
  ],
  "expect": {
    "throws": "not starting with \"$\""
  }
}