if (requiet("survival")) {
  m1 <- survfit(Surv(time, status) ~ sex + age + ph.ecog, data = lung)

  test_that("model_info", {
    expect_true(model_info(m1)$is_logit)
    expect_false(model_info(m1)$is_linear)
  })

  test_that("find_predictors", {
    expect_identical(find_predictors(m1), list(conditional = c("sex", "age", "ph.ecog")))
    expect_null(find_predictors(m1, effects = "random"))
  })

  test_that("find_response", {
    expect_identical(find_response(m1), "Surv(time, status)")
    expect_identical(find_response(m1, combine = FALSE), c("time", "status"))
  })

  test_that("link_inverse", {
    expect_equal(link_inverse(m1)(0.2), plogis(0.2), tolerance = 1e-5)
  })

  test_that("get_data", {
    expect_equal(nrow(get_data(m1)), 227)
    expect_equal(
      colnames(get_data(m1)),
      c("time", "status", "sex", "age", "ph.ecog")
    )
  })

  test_that("find_formula", {
    expect_length(find_formula(m1), 1)
    expect_equal(
      find_formula(m1),
      list(conditional = as.formula(
        "Surv(time, status) ~ sex + age + ph.ecog"
      )),
      ignore_attr = TRUE
    )
  })

  test_that("find_variables", {
    expect_equal(find_variables(m1), list(
      response = c("time", "status"),
      conditional = c("sex", "age", "ph.ecog")
    ))
    expect_equal(
      find_variables(m1, flatten = TRUE),
      c("time", "status", "sex", "age", "ph.ecog")
    )
  })

  test_that("n_obs", {
    expect_equal(n_obs(m1), 227)
  })

  test_that("linkfun", {
    expect_false(is.null(link_function(m1)))
  })

  test_that("is_multivariate", {
    expect_false(is_multivariate(m1))
  })

  test_that("find_terms", {
    expect_equal(
      find_terms(m1),
      list(
        response = "Surv(time, status)",
        conditional = c("sex", "age", "ph.ecog")
      )
    )
  })

  test_that("find_statistic", {
    expect_null(find_statistic(m1))
  })
}
