{
  "description": "Bid request with an unknown bidder name or alias inside the request.user.ext.unknown object",
  "mockBidRequest": {
    "id": "request-without-user-ext-obj",
    "site": {
      "page": "test.somepage.com"
    },
    "imp": [
      {
        "id": "my-imp-id",
        "banner": {
          "format": [
            {
              "w": 300,
              "h": 600
            }
          ]
        },
        "ext": {
          "appnexus": {
            "placementId": 12883451
          }
        }
      }
    ],
    "user": {
      "ext": {
        "prebid": {
          "buyeruids": {
            "unknown": "123"
          }
        }
      }
    }
  },
  "expectedReturnCode": 400,
  "expectedErrorMessage": "Invalid request: request.user.ext.unknown is neither a known bidder name nor an alias in request.ext.prebid.aliases\n"
}