firestore/internal/conformance/testdata/set-nodel.json

{
  "tests": [
    {
      "description": "set: Delete cannot appear in data",
      "comment": "The Delete sentinel cannot be used in Create, or in Set without a Merge option.",
      "set": {
        "docRefPath": "projects/projectID/databases/(default)/documents/C/d",
        "jsonData": "{\"a\": 1, \"b\": \"Delete\"}",
        "isError": true
      }
    }
  ]
}