firestore/internal/conformance/testdata/set-merge-prefix.json

{
  "tests": [
    {
      "description": "set-merge: One merge path cannot be the prefix of another",
      "comment": "The prefix would make the other path meaningless, so this is\nprobably a programming error.",
      "set": {
        "docRefPath": "projects/projectID/databases/(default)/documents/C/d",
        "option": {
          "fields": [
            {
              "field": [
                "a"
              ]
            },
            {
              "field": [
                "a",
                "b"
              ]
            }
          ]
        },
        "jsonData": "{\"a\": {\"b\": 1}}",
        "isError": true
      }
    }
  ]
}