{
  "_comment": [
    "Inputs only. Expectations are measured -- see record.js.",
    "`$setOnInsert`, the only update operator whose meaning depends on which",
    "branch of an upsert ran. Every case here is therefore a pair: the same",
    "update against a document that exists and against one that does not."
  ],
  "documents": [{ "_id": 1, "k": 1, "a": 100 }],
  "cases": [
    {
      "description": "$setOnInsert writes when the upsert inserts",
      "documents": [],
      "operation": "updateOne",
      "arguments": {
        "filter": { "k": 1 },
        "update": { "$setOnInsert": { "a": 1 }, "$set": { "b": 2 } },
        "upsert": true
      }
    },
    {
      "description": "$setOnInsert is ignored when the upsert updates",
      "operation": "updateOne",
      "arguments": {
        "filter": { "k": 1 },
        "update": { "$setOnInsert": { "a": 1 }, "$set": { "b": 2 } },
        "upsert": true
      }
    },
    {
      "description": "$setOnInsert alone on a plain update is a no-op",
      "operation": "updateOne",
      "arguments": {
        "filter": { "k": 1 },
        "update": { "$setOnInsert": { "a": 1 } }
      }
    },
    {
      "description": "$setOnInsert alone on an insert is the whole document",
      "documents": [],
      "operation": "updateOne",
      "arguments": {
        "filter": { "k": 7 },
        "update": { "$setOnInsert": { "a": 1 } },
        "upsert": true
      }
    },
    {
      "description": "$setOnInsert writes a dotted path on insert",
      "documents": [],
      "operation": "updateOne",
      "arguments": {
        "filter": { "k": 1 },
        "update": { "$setOnInsert": { "x.y": 5 } },
        "upsert": true
      }
    },
    {
      "description": "$setOnInsert may not touch _id",
      "documents": [],
      "operation": "updateOne",
      "arguments": {
        "filter": { "k": 1 },
        "update": { "$setOnInsert": { "_id": 9 } },
        "upsert": true
      }
    },
    {
      "description": "$setOnInsert and $set naming the same field on an insert",
      "documents": [],
      "operation": "updateOne",
      "arguments": {
        "filter": { "k": 1 },
        "update": { "$setOnInsert": { "a": 1 }, "$set": { "a": 2 } },
        "upsert": true
      }
    },
    {
      "description": "findOneAndUpdate reports the document $setOnInsert built",
      "documents": [],
      "operation": "findOneAndUpdate",
      "arguments": {
        "filter": { "k": 3 },
        "update": { "$setOnInsert": { "a": 1 } },
        "upsert": true,
        "returnDocument": "after"
      }
    },
    {
      "description": "updateMany with $setOnInsert on an upsert that inserts",
      "documents": [],
      "operation": "updateMany",
      "arguments": {
        "filter": { "k": 1 },
        "update": { "$setOnInsert": { "a": 1 } },
        "upsert": true
      }
    }
  ]
}