{
  "version": 8,
  "glyphs": "https://example.com/{fontstack}/{range}",
  "sources": {
    "vector": {
      "type": "vector",
      "url": "mapbox://mapbox.mapbox-streets-v5"
    }
  },
  "layers": [
    {
      "id": "minimum",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["Helvetica"],
        "text-field": "{foo}"
      }
    },
    {
      "id": "valid expression - case",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["case", ["==", "a", ["string", ["get", "text-font"]]], ["literal", ["Arial"]], ["literal", ["Helvetica"]]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "valid expression - match",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["match", ["get", "text-font"], "a", ["literal", ["Arial"]], ["literal", ["Helvetica"]]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "valid expression - step",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["array", "string", ["step", ["get", "text-font"], ["literal", ["Arial"]], 0, ["literal", ["Helvetica"]]]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "invalid expression - get",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["array", "string", ["get", "text-font"]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "invalid expression - case",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["case", ["==", "a", ["string", ["get", "text-font"]]], ["array", "string", ["get", "text-font-a"]], ["literal", ["Helvetica"]]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "invalid expression - match",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["match", ["get", "text-font"], "a", ["array", "string", ["get", "text-font-a"]], ["literal", ["Helvetica"]]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "invalid expression - at",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["array", "string", ["at", 0, ["array", ["get", "text-font"]]]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "invalid expression - coalesce",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["array", "string", ["coalesce", ["get", "text-font"]]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "invalid expression - step",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["step", ["zoom"], ["array", "string", ["get", "text-font-0"]], 0, ["array", "string", ["get", "text-font-1"]]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "invalid expression - let/var",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": ["let", "p", ["array", "string", ["get", "text-font"]], ["var", "p"]],
        "text-field": "{foo}"
      }
    },
    {
      "id": "invalid expression - identity function",
      "type": "symbol",
      "source": "vector",
      "source-layer": "layer",
      "layout": {
        "text-font": {
          "type": "identity",
          "property": "text-font"
        },
        "text-field": "{foo}"
      }
    }
  ]
}