implement prune_identical_backups() and doc, see #9

NAMESPACE

@@ -15,6 +15,7 @@ export(n_backups)
 export(newest_backup)
 export(oldest_backup)
 export(prune_backups)
+export(prune_identical_backups)
 export(rotate)
 export(rotate_date)
 export(rotate_rds)

R/BackupQueue.R

@@ -59,6 +59,14 @@ BackupQueue <- R6::R6Class(
     },
 
 
+
+    #' @description Delete all identical backups. Uses [tools::md5sum()] to
+    #'   compare the files.
+    prune_identical = function(){
+      NotImplementedError()
+    },
+
+
     print = function(){
       cat(fmt_class(class(self)[[1]]), "\n\n")
 

R/rotate.R

@@ -307,3 +307,34 @@ prune_backups <- function(
   invisible(file)
 }
 
+
+
+
+#' @description `prune_backups()` physically deletes all backups of a file
+#'   based on `max_backups`
+#' @section Side Effects:
+#' `prune_backups()` may delete files, depending on `max_backups`.
+#' @export
+#' @rdname rotate
+prune_identical_backups <- function(
+  file,
+  dir = dirname(file),
+  dry_run = FALSE,
+  verbose = dry_run
+){
+  assert_pure_BackupQueue(file, dir = dir)
+  assert(is_scalar_character(file))
+
+  if (dry_run){
+    DRY_RUN$activate()
+    on.exit(DRY_RUN$deactivate())
+  }
+
+  bq <- BackupQueueIndex$new(file, dir = dir)
+
+  if (!bq$has_backups)
+    bq <- BackupQueueDateTime$new(file, dir = dir)
+
+  bq$prune_identical()
+  invisible(file)
+}

tests/testthat/test_rotate.R

@@ -123,3 +123,36 @@ test_that("backup/rotate dry_run", {
 
   expect_snapshot_unchanged(snap)
 })
+
+
+
+
+test_that("BackupQueueIndex: $prune_identical works", {
+  tf <- file.path(td, "test")
+
+  saveRDS(iris, tf)
+  iris_md5 <- tools::md5sum(tf)
+  bq <- BackupQueueIndex$new(tf)
+  on.exit({
+    bq$prune(0)
+    unlink(tf)
+  })
+  backup(tf)
+  backup(tf)
+  rotate(tf)
+
+  saveRDS(cars, tf)
+  cars_md5 <- tools::md5sum(tf)
+  backup(tf)
+  saveRDS(cars, tf)
+  rotate(tf)
+
+  saveRDS(iris, tf)
+
+  prune_identical_backups(tf)
+
+  expect_identical(
+    unname(tools::md5sum(bq$files$path)),
+    unname(c(cars_md5, iris_md5))
+  )
+})