inferr: Inferential Statistics

context("binomtest")

test_that("output from infer_binom_calc matches the expected output", {
  k <- infer_binom_calc(32, 8)
  expect_equal(k$n, 32)
  expect_equal(k$k, 8)
  expect_equal(k$exp_k, 16)
  expect_equal(k$obs_p, 0.25)
  expect_equal(k$exp_p, 0.5)
  expect_equal(k$pval_lower, 0.0035)
  expect_equal(k$pval_upper, 0.998949)


  k <- infer_binom_calc(32, 20)
  expect_equal(k$n, 32)
  expect_equal(k$k, 20)
  expect_equal(k$exp_k, 16)
  expect_equal(k$obs_p, 0.625)
  expect_equal(k$exp_p, 0.5)
  expect_equal(k$pval_lower, 0.944908)
  expect_equal(k$pval_upper, 0.107664)
})

test_that("infer_binom_calc throws the appropriate error", {
  expect_error(infer_binom_calc("32", 20), "n must be an integer")
  expect_error(infer_binom_calc(32, "20"), "success must be an integer")
  expect_error(infer_binom_calc(32, 20, "0.5"), "prob must be numeric")
  expect_error(infer_binom_calc(32, 20, 1.5), "prob must be between 0 and 1")
  expect_error(infer_binom_calc(32, 20, -1.5), "prob must be between 0 and 1")
})


mt <- mtcars
mt$vs <- as.factor(mt$vs)
mt$am <- as.factor(mt$am)

test_that("output from infer_binom_test matches the expected output", {
  k <- infer_binom_test(mt, vs)
  expect_equal(k$n, 32)
  expect_equal(k$k, 14)
  expect_equal(k$exp_k, 16)
  expect_equal(k$obs_p, 0.4375)
  expect_equal(k$exp_p, 0.5)
  expect_equal(k$pval_lower, 0.298307)
  expect_equal(k$pval_upper, 0.811457)
})

test_that("infer_binom_test throws the appropriate error", {
  expect_error(infer_binom_test(mtcars, mpg), "variable must be of type factor")
  expect_error(infer_binom_test(mt, am, "0.5"), "prob must be numeric")
  expect_error(infer_binom_test(mt, am, 1.5), "prob must be between 0 and 1")
  expect_error(infer_binom_test(mt, am, -1.5), "prob must be between 0 and 1")
})


test_that("output from infer_binom_calc is as expected when k < exp_k", {
  x <- cat("            Binomial Test
 --------------------------------------
           Group    N     Obs. Prop    Exp. Prop
           --------------------------------------
           0      24         0.75        0.500
           1       8         0.25        0.500
           --------------------------------------


           Test Summary
           ------------------------------------------
           Tail             Prob            p-value
           ------------------------------------------
           Lower         Pr(k <= 8)          0.0035
           Upper         Pr(k >= 8)         0.998949
           ------------------------------------------")

  expect_equivalent(print(infer_binom_calc(32, 8)), x)
})

test_that("output from infer_binom_calc is as expected when k > exp_k", {
  x <- cat("            Binomial Test
 --------------------------------------
           Group    N     Obs. Prop    Exp. Prop
           --------------------------------------
           0      12        0.375        0.500
           1      20        0.625        0.500
           --------------------------------------


           Test Summary
           --------------------------------------------
           Tail              Prob             p-value
           --------------------------------------------
           Lower         Pr(k <= 20)          0.944908
           Upper         Pr(k >= 20)          0.107664
           --------------------------------------------")

  expect_equivalent(print(infer_binom_calc(32, 20)), x)
})