Use `expect_snapshot()` instead of `expect_error()` and `expect_message()`

[EmilHvitfeldt]

If you are not careful enough with the expectation in these function you might end up getting false negatives.
I would suggest you use expect_snapshot() instead.

Before

expect_error(prep(rec, training = dat), "name")

  expect_message(prep(rec2, training = dat2), "[Nn]ew names")

After

expect_snapshot(
  error = TRUE,
  prep(rec, training = dat)
)

expect_snapshot(
  prep(rec2, training = dat2)
)