test_that("Dirichlet density can be computed", {
  x <- c(0.5, 0.3, 0.2)
  concentration <- 1:3
  factor <- 1000
  expect_equal(
    round(ddirichlet(x = x, concentration = concentration, log = FALSE) * factor) / factor,
    0.72
  )
  expect_equal(
    round(ddirichlet(x = x, concentration = concentration, log = TRUE) * factor) / factor,
    -0.329
  )
  expect_error(
    ddirichlet(x = c(0.5, 0.3, 0.3), concentration = concentration),
    "'x' must sum up to 1"
  )
})

test_that("Multivariate normal density can be computed", {
  x <- c(0, 0)
  mean <- c(0, 0)
  Sigma <- diag(2)
  factor <- 1000
  expect_equal(
    round(dmvnorm(x = x, mean = mean, Sigma = Sigma, log = FALSE) * factor) / factor,
    0.159
  )
  expect_equal(
    round(dmvnorm(x = x, mean = mean, Sigma = Sigma, log = TRUE) * factor) / factor,
    -1.838
  )
  expect_error(
    dmvnorm(x = 1:2, mean = 1:3, Sigma = diag(4)),
    "Assertion on 'mean' failed: Must have length 2, but has length 3."
  )
})

test_that("(Inverse-) Wishart density can be computed", {
  x <- diag(2)
  df <- 4
  scale <- matrix(c(1, 0.2, 0.2, 2), 2, 2)
  factor <- 1000
  expect_equal(
    round(dwishart(x = x, df = df, scale = scale, log = FALSE, inv = FALSE) * factor) / factor,
    0.005
  )
  expect_equal(
    round(dwishart(x = x, df = df, scale = scale, log = TRUE, inv = FALSE) * factor) / factor,
    -5.335
  )
  expect_equal(
    round(dwishart(x = x, df = df, scale = scale, log = FALSE, inv = TRUE) * factor) / factor,
    0.034
  )
  expect_equal(
    round(dwishart(x = x, df = df, scale = scale, log = TRUE, inv = TRUE) * factor) / factor,
    -3.378
  )
  expect_error(
    dmvnorm(dwishart(x = x, df = 1, scale = scale)),
    "Assertion on 'df' failed: Element 1 is not >= 2."
  )
})