firestore/internal/conformance/testdata/update-fp-empty-component.json

{
  "tests": [
    {
      "description": "update: empty field path component",
      "comment": "Empty fields are not allowed.",
      "update": {
        "docRefPath": "projects/projectID/databases/(default)/documents/C/d",
        "jsonData": "{\"a..b\": 1}",
        "isError": true
      }
    }
  ]
}