Add min_length to check_character()

[olivroy]

Sometimes you want something non-empty. allow_zero = FALSE will disallow character(0). Addresses #1618 (comment)

[lionel-]

I think this should be allow_empty and apply to all vector types?

Could also be something like length = c("any", "non_empty", "scalar")? It seems like this change deserves some discussion about general vector checks.

[olivroy]

I agree. However allow_empty would be confusing since for check_string(). allow_empty = FALSE is meant to disallow "".

I like the length argument. maybe min_length would be good?

the proposed scalar option would be redundant since check_string() is already there.

[olivroy]

Modify the stop_input_type() call for:

  what <- "character vector"  
  if (min_length > 0) {
    what <- paste0(what, "of length greater or equal to", min_length) 
  }