test_that('check default engines', {
  expect_equal(boost_tree()$engine, "xgboost")
  expect_equal(decision_tree()$engine, "rpart")
  expect_equal(linear_reg()$engine, "lm")
  expect_equal(logistic_reg()$engine, "glm")
  expect_equal(mars()$engine, "earth")
  expect_equal(mlp()$engine, "nnet")
  expect_equal(multinom_reg()$engine, "nnet")
  expect_equal(nearest_neighbor()$engine, "kknn")
  expect_equal(proportional_hazards()$engine, "survival")
  expect_equal(rand_forest()$engine, "ranger")
  expect_equal(survival_reg()$engine, "survival")
  expect_equal(svm_linear()$engine, "LiblineaR")
  expect_equal(svm_poly()$engine, "kernlab")
  expect_equal(svm_rbf()$engine, "kernlab")
})