test_that("TZ2UTC converts dates to correct UTC offsets for America/Toronto", {
  # Input dates: one in DST (October 24, 2017) and one after DST ends (November 20, 2017)
  x <- as.Date(c("2017-10-24", "2017-11-20"))
  result <- TZ2UTC(DT = x, TZ = "America/Toronto")

  # Expected offsets: UTC-04:00 during DST, UTC-05:00 after DST
  expected <- c("UTC-04:00", "UTC-05:00")

  # Check type and length
  expect_type(result, "character")
  expect_length(result, length(expected))

  # Check values
  expect_equal(result, expected)
})