viztest_fixture_model <- function() {
  dat <- mtcars
  dat$cyl <- as.factor(dat$cyl)
  dat$hp  <- scale(dat$hp)
  dat$wt  <- scale(dat$wt)
  stats::lm(qsec ~ hp + wt + cyl, data = dat)
}

viztest_fit <- function(...) {
  VizTest::viztest(viztest_fixture_model(), ...)
}

viztest_chick_model <- function() {
  data("chickwts", package = "datasets")
  chickwts$feed <- as.factor(chickwts$feed)
  stats::lm(weight ~ feed, data = chickwts)
}

viztest_chick_estimates <- function() {
  data("chickwts", package = "datasets")
  m <- stats::lm(weight ~ feed, data = chickwts)
  marginaleffects::predictions(m, variables="feed", by="feed")
}


viztest_chick_vt_data <- function() {
  data("chickwts", package = "datasets")
  m <- stats::lm(weight ~ feed, data = chickwts)
  preds <- marginaleffects::predictions(m, variables="feed", by="feed")
  b <- coef(preds)
  names(b) <- preds$feed
  v <- vcov(preds)
  make_vt_data(b, v)
}