test_that("global engine", {
  skip_on_cran()
  skip_if_not(
    find_proglang("julia"),
    message = "skip test as julia installation not found."
  )

  data(voters)
  lm_fit <-
    lm(proposition_vote ~ treatment + ideology1 + log_income + Q1_immigration,
      data = voters
    )

  boot1 <-
    boottest(lm_fit,
      param = "treatment",
      B = 999,
      clustid = "group_id1"
    )
  boot2 <-
    suppressWarnings(
      boottest(
        lm_fit,
        param = "treatment",
        B = 999,
        clustid = "group_id1",
        engine = "WildBootTests.jl"
      )
    )

  expect_equal(boot1$engine, "R")
  expect_equal(boot2$engine, "WildBootTests.jl")

  # leave state of global variables clean
  setBoottest_engine(engine = "WildBootTests.jl")
  # switch back to "R" as global variable at end of function
  on.exit(setBoottest_engine(engine = "R"), add = TRUE)
  boot1 <-
    suppressWarnings(boottest(
      lm_fit,
      param = "treatment",
      B = 999,
      clustid = "group_id1"
    ))
  boot2 <-
    suppressWarnings(boottest(
      lm_fit,
      param = "treatment",
      B = 999,
      clustid = "group_id1"
    ))
  boot3 <-
    boottest(
      lm_fit,
      param = "treatment",
      B = 999,
      clustid = "group_id1",
      engine = "R"
    )

  expect_equal(boot1$engine, "WildBootTests.jl")
  expect_equal(boot2$engine, "WildBootTests.jl")
  expect_equal(boot3$engine, "R")
})




# test_that("global nthreads", {
#   skip_on_ci()
#   skip_on_cran()
#
#   data(voters)
#   lm_fit <-
#     lm(proposition_vote ~ treatment + ideology1 + log_income + Q1_immigration,
#        data = voters)
#
#   boot1 <-
#     boottest(lm_fit,
#              param = "treatment",
#              B = 999,
#              clustid = "group_id1")
#   boot2 <-
#     boottest(
#       lm_fit,
#       param = "treatment",
#       B = 999,
#       clustid = "group_id1",
#       nthreads = 4
#     )
#   boot3 <-
#     boottest(
#       lm_fit,
#       param = "treatment",
#       B = 999,
#       clustid = "group_id1",
#       nthreads = 0.5
#     )
#
#   expect_equal(boot1$nthreads, 1)
#   expect_equal(boot2$nthreads, 4)
#   expect_equal(boot3$nthreads, 4)
#
#   setBoottest_nthreads(4)
#   expect_equal(getOption("boottest_nthreads"), 4)
#   expect_equal(getBoottest_nthreads(), 4)
#   # switch back to "R" as global variable at end of function
#   on.exit(setBoottest_nthreads(), add = TRUE)
#
#   boot3 <-
#     boottest(lm_fit,
#              param = "treatment",
#              B = 999,
#              clustid = "group_id1")
#   boot4 <-
#     boottest(
#       lm_fit,
#       param = "treatment",
#       B = 999,
#       clustid = "group_id1",
#       nthreads = 2
#     )
#
#   expect_equal(boot3$nthreads, 4)
#   expect_equal(boot4$nthreads, 2)
# })