tests/testthat/test_calculate_curvature.R

In k-t-to/gravee: Good Risk Assessment Values for Environmental Exposures

context("calculate_curvature.R")

test_that("Does Menger Curvature calculation perform as expected?", {
  # Does the function stop if the input vectors are incorrect length?
  expect_error(calculate_menger_curvature(1:2, 1:2))
  expect_error(calculate_menger_curvature(1:4, 1:4))
  # Does the function return only a single value?
  expect_length(calculate_menger_curvature(c(1, 1.5, 8), c(5, 5.8, 12)), 1)
  # Are straight lines and identical points calculated correctly?
  expect_equal(calculate_menger_curvature(c(1, 2, 3), c(1, 2, 3)), 0)
  expect_true(is.nan(calculate_menger_curvature(c(1, 1, 1), c(1, 1, 1))))
  # Do we get the expected output?
  x <- c(1, 2, 3)
  y <- c(1, 4, 9)
  z <- round(calculate_menger_curvature(x, y), 2)
  expect_equal(z, 0.03)
  # Do the output make sense?
  y_2 <- c(2, 3, 9)
  a <- calculate_menger_curvature(x, y_2)
  expect_gt(a, z)
})

test_that("Does Menger Curvature function match hand calculation?", {
  expect_equal(round(calculate_menger_curvature(c(1, 3, 5), c(2, 3, 6)), 6), 0.175412)
  expect_equal(round(calculate_menger_curvature(c(40, 50, 52), c(43, 63, 70)), 6), 0.012474)
  expect_equal(round(calculate_menger_curvature(c(0, 1, 2), c(1, 0.5, 1.5)), 6), 0.920358)
})

test_that("Does the correct POD get returned from MC calculations?", {
  sim_predictedDR <- list(
    x = 1:10,
    y = sin(1:10)
  )
  pred_out <- calculate_spline_curvature(sim_predictedDR)
  expect_equal(pred_out$log10_dose[which.max(pred_out$mc)], 8)
})