assertFailsWith<IllegalArgumentException> {
      Request.Builder()
        .url(server.url("/"))
        .header("", "A")
        .build()
    }
  }

  @Test
  fun emptyResponseHeaderNameIsLenient() {
    val headers = Headers.Builder()
    addHeaderLenient(headers, ":A")
    server.enqueue(
      MockResponse(
        headers = headers.build(),
        body = "body",
      ),