test_that("objective with one target argument can be evaluated", {
  f <- function(x, a, b = 0) (x + a)^2 + b
  objective <- Objective$new(objective = f, target = "x", npar = 1, a = -2)
  objective$verbose <- FALSE
  expect_equal(
    objective$get_argument("b"),
    0
  )
  expect_equal(
    objective$evaluate(2),
    0
  )
  expect_silent(
    objective$remove_argument("a")
  )
  expect_error(
    objective$evaluate(2),
    "Function evaluation threw an error"
  )
  expect_silent(
    objective$set_argument("a" = -2)
  )
  expect_error(
    objective$set_argument("a" = -2, overwrite = FALSE),
    "already exists"
  )
  expect_silent(
    objective$set_argument("a" = -2, overwrite = TRUE)
  )
  expect_equal(
    objective$evaluate(2),
    0
  )
  expect_snapshot(
    print(objective)
  )
})

test_that("objective with more than one target argument can be evaluated", {
  llk <- function(mu, sd, lambda, data) {
    sd <- exp(sd)
    lambda <- plogis(lambda)
    sum(log(lambda * dnorm(data, mu[1], sd[1]) + (1 - lambda) * dnorm(data, mu[2], sd[2])))
  }
  objective <- Objective$new(
    objective = llk, target = c("mu", "sd", "lambda"), npar = c(2, 2, 1),
    data = faithful$eruptions
  )
  objective$verbose <- FALSE
  expect_equal(
    objective$get_argument("data"),
    faithful$eruptions
  )
  expect_snapshot(
    print(objective)
  )
  expect_equal(
    objective$evaluate(1:5),
    llk(mu = 1:2, sd = 3:4, lambda = 5, data = faithful$eruptions)
  )
  expect_equal(
    objective$evaluate(1:5, .negate = TRUE),
    -llk(mu = 1:2, sd = 3:4, lambda = 5, data = faithful$eruptions)
  )
})