firestore/internal/conformance/testdata/update-st-alone.json

{
  "tests": [
    {
      "description": "update: ServerTimestamp alone",
      "comment": "If the only values in the input are ServerTimestamps, then no\nupdate operation should be produced.",
      "update": {
        "docRefPath": "projects/projectID/databases/(default)/documents/C/d",
        "jsonData": "{\"a\": \"ServerTimestamp\"}",
        "request": {
          "database": "projects/projectID/databases/(default)",
          "writes": [
            {
              "transform": {
                "document": "projects/projectID/databases/(default)/documents/C/d",
                "fieldTransforms": [
                  {
                    "fieldPath": "a",
                    "setToServerValue": "REQUEST_TIME"
                  }
                ]
              },
              "currentDocument": {
                "exists": true
              }
            }
          ]
        }
      }
    }
  ]
}