test_that("test whether psd_spade function works well", {
  data('NTDs')
  wt = sdsfun::inverse_distance_swm(sf::st_as_sf(NTDs,coords = c('X','Y')),power = 2)
  p = round(psd_spade(NTDs$incidence,NTDs$soiltype,wt),6)
  expect_equal(p,0.256653)
})