test_that("entropy_d works correctly", {
  lx <- 0.8^(0:8)
  mx <- c(0.00, 0.00, 1.10, 1.50, 1.60, 1.70, 1.50, 1.20, 0.70)

  x <- entropy_d(lx, mx)

  expect_length(x, 1L)
  expect_gt(x, 0)
})

test_that("entropy_d warns and fails gracefully", {
  lx1 <- c(1.1, 0.6, 0.5, 0.4) # lx is greater than 1
  mx1 <- c(4.4, 3.3, 2.2, 1.1)
  expect_error(entropy_d(lx1, mx1))

  lx2 <- c(1.0, 0.6, 0.61, 0.5) # lx not monotonically declining
  mx2 <- c(4.4, 3.3, 2.2, 1.1)
  expect_error(entropy_d(lx2, mx2))

  lx3 <- c(1.0, 0.6, 0.6, 0.5) # negative mx
  mx3 <- c(4.4, 3.3, 2.2, -0.1)
  expect_error(entropy_d(lx3, mx3))
})