{
  "description": "Bid request with an empty native.request field in its only imp element",
  "mockBidRequest": {
    "id": "req-id",
    "site": {
      "page": "some.page.com"
    },
    "tmax": 500,
    "imp": [
      {
        "id": "some-imp",
        "native": {
          "request": "{}"
        },
        "ext": {
          "appnexus": {
            "placementId": 12883451
          }
        }
      }
    ]
  },
  "expectedReturnCode": 400,
  "expectedErrorMessage": "Invalid request: request.imp[0].native.request.assets must be an array containing at least one object"
}