test_that("choice-experiment WTP is -beta/beta_cost", {
  b <- c(a = 0.8, b = -0.2, cost = -0.01)
  V <- diag(c(1e-8, 1e-8, 1e-12))
  dimnames(V) <- list(names(b), names(b))
  set.seed(1)
  w <- wtp_estimates(coef = b, vcov = V, cost = "cost")
  expect_equal(w$estimate, c(80, -20))
  expect_equal(w$kr_mean, c(80, -20), tolerance = 1e-2)
  expect_true(all(w$lower <= w$estimate & w$upper >= w$estimate))
  expect_output(print(w), "Krinsky-Robb")
})

test_that("dichotomous-choice WTP from glm recovers the truth", {
  set.seed(3)
  bid <- sample(c(20, 50, 100, 200, 400), 3000, replace = TRUE)
  yes <- rbinom(3000, 1, plogis(2 - 0.01 * bid))
  m <- glm(yes ~ bid, family = binomial)
  set.seed(4)
  w <- wtp_estimates(m, cost = "bid", type = "dichotomous", n_draws = 500)
  expect_equal(w$estimate, 200, tolerance = 0.1)
  expect_equal(w$estimate, unname(-coef(m)[1] / coef(m)[2]))
})

test_that("wtp input checks", {
  expect_error(wtp_estimates(coef = c(a = 1), vcov = diag(1), cost = "z"))
  expect_error(wtp_estimates(cost = "x"))
  b <- c(bid = -0.01)
  V <- matrix(1e-6, 1, 1, dimnames = list("bid", "bid"))
  expect_error(wtp_estimates(coef = b, vcov = V, cost = "bid",
                             type = "dichotomous"), "Intercept")
})