TestCreateWebSocket(url: string, options?: WebSocketOptions): Task<WebSocket>;

readonly createdUrls: string[];

readonly message: (url: string, data:
  | string
  | Blob
  | ArrayBuffer) => void;

readonly open: (url: string) => void;

readonly sentMessages: {
  data: string | Blob | Uint8Array<ArrayBufferLike> | BufferSource;
  url: string;
}[];