{
  "propertySpec": {
    "type": "string",
    "property-type": "data-driven",
    "expression": {"parameters": ["zoom", "feature"]}
  },
  "expression": ["case", ["get", "x"], "x", ["get", "y"], "y", "otherwise"],
  "inputs": [
    [{}, {"properties": {"x": true, "y": true}}],
    [{}, {"properties": {"x": true, "y": false}}],
    [{}, {"properties": {"x": false, "y": true}}],
    [{}, {"properties": {"x": false, "y": false}}],
    [{}, {"properties": {"x": "false", "y": false}}]
  ],
  "expected": {
    "compiled": {
      "result": "success",
      "isFeatureConstant": false,
      "isZoomConstant": true,
      "type": "string"
    },
    "outputs": [
      "x",
      "x",
      "y",
      "otherwise",
      {
        "error": "Expected value to be of type boolean, but found string instead."
      }
    ],
    "serialized": [
      "case",
      ["boolean", ["get", "x"]],
      "x",
      ["boolean", ["get", "y"]],
      "y",
      "otherwise"
    ]
  }
}