test_that("AppenderDynatrace: appending works", {
  event <- lgr::LogEvent$new(
    logger = lgr::Logger$new("dummy"),
    level = 300,
    timestamp = structure(1541175573.9308, class = c("POSIXct", "POSIXt"), tzone = "UTC"),
    caller = NA_character_,
    msg = "foo bar"
  )

  # arrange
  app <- AppenderDynatrace$new(url = "http://foo.bar", api_key = "hashbaz")


  httr_response_mock <- function(req) {
    sent_request <<- req
    httr2::response(status_code = 204)
  }

  httr2::local_mocked_responses(httr_response_mock)

  # act
  app$append(event)

  # assert
  sent_body <- sent_request$body$data

  sent_body

  expect_identical(
    sent_body,
    "[{\"level\":\"warn\",\"timestamp\":\"2018-11-02 16:19:33\",\"logger\":\"dummy\",\"caller\":null,\"content\":\"foo bar\"}]")

  if (utils::packageVersion("httr2") >= "1.1.2.9000") {
    headers <- httr2::req_get_headers(sent_request, "reveal")
  } else {
    headers <- sent_request$headers
  }
  
  expect_identical(headers[["Content-Type"]], "application/json")
  expect_identical(headers[["Authorization"]], "Api-Token hashbaz")
})