assertive programming: tidy stopifnot

[AnthonyEbert]

A tidy version of stopifnot which respects groups

stop_if_not <- function(.data, ...){
  
  statements <- rlang::quos(...)
  
  dplyr::mutate(.data, stopifnot(!!!statements))
  
  return(.data)
}

Example

iris |> group_by(Species) |> stop_if_not(n() == 50)
# Passes

iris |> group_by(Species) |> stop_if_not(n() != 50)
# Fails

starwars |> stop_if_not(n_distinct(name) == n()) 
# Passes

starwars |> stop_if_not(if_all(where(is.numeric), ~ .x > 0))
# Fails

starwars |> stop_if_not(if_all(where(is.numeric), ~ .x > 0 | is.na(.x)))
# Passes

[DavisVaughan]

I think such an assertion is out of scope for dplyr and is really its own package. pointblank does this well https://rstudio.github.io/pointblank/