tests/testthat/test_posteriors_chi_squared.R

In greta-dev/greta: Simple and Scalable Statistical Modelling in R

test_that("samplers are unbiased for chi-squared", {
  skip_if_not(check_tf_version())
  skip_on_os("windows")
  df <- 5
  x <- chi_squared(df)
  iid <- function(n) rchisq(n, df)

  chi_squared_checked <- check_samples(
    x = x,
    iid_function = iid,
    sampler = hmc()
  )

  # do the plotting
  qqplot_checked_samples(chi_squared_checked)

  # do a formal hypothesis test
  stat <- ks_test_mcmc_vs_iid(chi_squared_checked)

  expect_gte(stat$p.value, 0.01)
})