Add grouped reporting of dupe rows:

set.seed(14)
dat <- data.frame(mtcars[sample(1:5, 14, TRUE), ])[sample.int(14), ]
rownames(dat) <- NULL
dat

library(dplyr)
add_rownames(dat) %>% 
      group_by_(.dots= names(dat)) %>% 
      filter(n()>1) %>%
      summarise(rn= paste(rowname, collapse=", "))%>%
      .$rn %>%
      paste0("(", ., ")", collapse="")

(3, 7, 8, 10, 11)(2, 13)(1, 4, 5, 6, 9)

turn into a function

has_files <- length(dir(path, pattern = paste0("\\.",test[["file"]][["type"]],"$")) )>0

vd_non_empty <- function(path){
  length(dir(path, pattern = paste0("\\.",test[["file"]][["type"]],"$")) )>0
}

currently we allow the patterns ##### or #####-#### ie 5 or 5 dash 4 format. That means a 9 digit without a dash fails. Should it?

The fix is to go from: "^\\d{5}(-\\d{4})?$" to "^\\d{5}(-?\\d{4})?$"

folders can be empty : vd_non_empty (actually we just fail it if main folder is empty)

folders can contain files that are completely empty : this is vf_non_empty

files can contain headers but no table data : this is vt_non_empty

tables can contain headers but no column data in required cols : this is vt_required