test_that("conjoint helpers work", {

  skip_if_not_installed("cjoint")

  library(dplyr)
  library(DeclareDesign)
  library(cjoint) # for the amce regression model

  # Design features
  N_subjects <- 500
  N_tasks <- 3

  # Attributes and levels
  levels_list =
    list(
      gender = c("Man", "Woman"),
      party = c("Left", "Right"),
      region = c("North", "South", "East", "West")
    )

  # Conjectured utility function
  conjoint_utility <-
    function(data){
      data |>
        mutate(U = 0.25*(gender == "Woman")*(region %in% c("North", "East")) +
                 0.5*(party == "Right")*(region %in% c("North", "South")) + uij)
    }

  declaration_17.5 <-
    declare_model(
      subject = add_level(N = N_subjects),
      task = add_level(N = N_tasks, task = 1:N_tasks),
      profile = add_level(
        N = 2,
        profile = 1:2,
        uij = rnorm(N, sd = 1)
      )
    ) +
    declare_inquiry(handler = conjoint_inquiries,
                    levels_list = levels_list,
                    utility_fn = conjoint_utility) +
    declare_assignment(handler = conjoint_assignment,
                       levels_list = levels_list) +
    declare_measurement(handler = conjoint_measurement,
                        utility_fn = conjoint_utility) +
    declare_estimator(choice ~ gender + party + region,
                      respondent.id = "subject",
                      .method = amce)

  expect_error(simulate_design(declaration_17.5, sims = 1), NA)

})