test_that("MSH segment parsing works", {
  msh_line <- "MSH|^~\\&|SAP-ISH|104|104|LEO|202301011200||ADT^A02|12345678|P|2.3"
  msh <- get_MSH(msh_line)
  expect_equal(msh$MESSAGE_CONTROL_ID, "12345678")
  expect_equal(msh$VERSION_ID, "2.3")
})

test_that("PID segment parsing works", {
  pid_line <- "PID|1||12345||SMITH^JOHN^^^^^L||19800101|M"
  pid <- get_PID(pid_line)
  expect_equal(pid$INTERNAL_PATIENT_ID, "12345")
  expect_equal(pid$FIRST_NAME, "JOHN")
  expect_equal(pid$LAST_NAME, "SMITH")
  expect_equal(pid$GENDER, "M")
})

test_that("EVN segment parsing works", {
  evn_line <- "EVN|A01|202301011200"
  evn <- get_EVN(evn_line)
  expect_equal(evn$EVENT_TYPE_CODE, "A01")
})

test_that("get_HL7_LINE works", {
  data <- c("MSH|...", "PID|...", "NK1|...")
  line <- get_HL7_LINE(data, "PID|")
  expect_true(grepl("^PID\\|", line))
})

test_that("get_DATE_TIME works", {
  dt <- get_DATE_TIME("20230101120000")
  expect_equal(dt$DATE, "20230101")
  expect_equal(dt$TIME, "120000")
})

test_that("empty input returns NULL", {
  expect_null(get_HL7_DATA(data = character(0)))
})