Update standalone files + standardize snapshot tests

[olivroy]

• update standalone with usethis::use_standalone("r-lib/rlang")
• Update snapshot tests to use a single exect_snapshot(error = TRUE) for each error
• Remove expect_error() inside snapshots as we no longer need the error class
• replace expect_warning(code, regexp = NA) by expect_no_warning()
• Require more recent testthat version
• Used testthat::set_max_fails(Inf) for faster iteration during development

[DavisVaughan]

Thanks! A few things to tweak across the board but otherwise looks great

[DavisVaughan]

I took a look at the updated snapshots. In all cases I believe we can drop cnd_class = TRUE.

Our advice lately is that if you really care about the error class, then you do

testthat::expect_error(class = )

and if you also care about the error message, you do a separate

testthat::expect_snapshot(error = )

But lately we have not been combining both features into a single snapshot

And in all cases here in tidyr I don't think we care about the error class

[olivroy]

Done in b49c272

[DavisVaughan]

Looks awesome thanks so much!