{
  "description": "Unexpected mongos",
  "uri": "mongodb://b/?replicaSet=rs",
  "phases": [
    {
      "responses": [
        [
          "b:27017",
          {
            "ok": 1,
            "helloOk": true,
            "isWritablePrimary": true,
            "msg": "isdbgrid",
            "minWireVersion": 0,
            "maxWireVersion": 6
          }
        ]
      ],
      "outcome": {
        "servers": {},
        "topologyType": "ReplicaSetNoPrimary",
        "logicalSessionTimeoutMinutes": null,
        "setName": "rs"
      }
    }
  ]
}