tests/testthat/test-eovcheck-engine.R

In s20x: Functions for University of Auckland Course STATS 201/208 Data Analysis

test_that("eovcheck keeps the base graphics engine as the default", {
  sampleData = data.frame(
    response = c(1.1, 1.9, 3.2, 3.8, 5.3, 5.7),
    predictor = c(1, 2, 3, 4, 5, 6)
  )
  fit = lm(response ~ predictor, data = sampleData)

  pdf(NULL)
  on.exit(dev.off(), add = TRUE)

  expect_silent(eovcheck(fit))
  expect_silent(eovcheck(fit, engine = "base"))
})


test_that("eovcheck validates the plotting engine argument", {
  sampleData = data.frame(
    response = c(1.1, 1.9, 3.2, 3.8, 5.3, 5.7),
    predictor = c(1, 2, 3, 4, 5, 6)
  )
  fit = lm(response ~ predictor, data = sampleData)

  expect_error(
    eovcheck(fit, engine = "lattice"),
    "'arg' should be one of",
    fixed = TRUE
  )
})


test_that("eovcheck ggplot2 engine returns a ggplot object when available", {
  skip_if_not_installed("ggplot2")

  sampleData = data.frame(
    response = c(1.1, 1.9, 3.2, 3.8, 5.3, 5.7),
    predictor = c(1, 2, 3, 4, 5, 6)
  )
  fit = lm(response ~ predictor, data = sampleData)

  plotObject = eovcheck(fit, engine = "ggplot2", smoother = TRUE, twosd = TRUE)

  expect_s3_class(plotObject, "ggplot")
})


test_that("eovcheck formula method passes engine and Levene arguments", {
  skip_if_not_installed("ggplot2")

  sampleData = data.frame(
    response = c(1, 2, 2, 3, 4, 4, 5, 6),
    group = factor(rep(c("a", "b"), each = 4))
  )

  plotObject = eovcheck(response ~ group, data = sampleData, engine = "ggplot2", levene = TRUE)

  expect_s3_class(plotObject, "ggplot")
})


test_that("eovcheck ggplot2 engine prints without aesthetic mapping warnings", {
  skip_if_not_installed("ggplot2")

  sampleData = data.frame(
    response = c(1.1, 1.9, 3.2, 3.8, 5.3, 5.7, 7.1, 8.2),
    predictor = c(1, 2, 3, 4, 5, 6, 7, 8)
  )
  fit = lm(response ~ predictor, data = sampleData)

  plotObject = eovcheck(fit, engine = "ggplot2")

  expect_s3_class(plotObject, "ggplot")
  expect_silent(print(plotObject))
})


test_that("eovcheck ggplot2 engine uses base-like theme and thin two sd lines", {
  skip_if_not_installed("ggplot2")

  sampleData = data.frame(
    response = c(1.1, 1.9, 3.2, 3.8, 5.3, 5.7, 7.1, 8.2),
    predictor = c(1, 2, 3, 4, 5, 6, 7, 8)
  )
  fit = lm(response ~ predictor, data = sampleData)

  plotObject = eovcheck(fit, engine = "ggplot2", twosd = TRUE)
  hlineLayers = plotObject$layers[vapply(plotObject$layers, function(layer) {
    inherits(layer$geom, "GeomHline")
  }, logical(1))]
  lineWidths = vapply(hlineLayers, function(layer) {
    layer$aes_params$linewidth
  }, numeric(1))

  expect_true(inherits(plotObject$theme$panel.grid.major, "element_blank"))
  expect_true(inherits(plotObject$theme$panel.background, "element_rect"))
  expect_true(any(lineWidths <= 0.5))
})