test_that("Center works", {
  expect_equal(center(1:3), c(-1, 0, 1))
  expect_equal(
    matrix(center(data.frame(rep(1, 3), rep(2, 3), rep(3, 3))), 3, 3),
    matrix(rep(-1:1, time2 = 3), 3, 3, byrow = TRUE)
  )
  expect_equal(
    matrix(center(dfts(data.frame(rep(1, 3), rep(2, 3), rep(3, 3))))$data, 3, 3),
    matrix(rep(-1:1, time2 = 3), 3, 3, byrow = TRUE)
  )
})

test_that("PCA works", {
  expect_equal(round(pca(1:10)$sdev, 5), 3.02765)
  expect_equal(
    round(pca(electricity)$sdev[1:3], 6),
    c(15.764828, 5.456613, 3.313120)
  )
})

test_that("SD works", {
  expect_equal(round(sd(1:10), 5), 3.02765)
  expect_equal(
    round(sd(electricity)[1:3], 5),
    c(16.35713, 16.34201, 16.39898)
  )
})

test_that("Var works", {
  expect_equal(round(var(1:10), 5), 9.16667)
  expect_equal(
    round(var(electricity, type = "pointwise")[1:3], 5),
    c(267.55565, 267.06142, 268.92667)
  )
  expect_equal(
    round(diag(var(electricity, type = "operator"))[1:3], 5),
    c(266.82262, 266.32974, 268.18988)
  )
})

test_that("CUSUM works", {
  expect_equal(
    round(cumsum(electricity)$data[c(1, 5, 10), 365], 5),
    c(14562.59, 10548.78, 16999.70)
  )
})