Warn about sas_numeric_to_date() timezone usage

sfirke · Nov 18, 2024 · 71f9736 · 71f9736
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Showing 5 changed files with 21 additions and 8 deletions.
diff --git a/DESCRIPTION b/DESCRIPTION
@@ -52,4 +52,4 @@ Config/testthat/edition: 3
 Encoding: UTF-8
 LazyData: true
 Roxygen: list(markdown = TRUE)
-RoxygenNote: 7.3.1
+RoxygenNote: 7.3.2
diff --git a/NEWS.md b/NEWS.md
@@ -31,7 +31,9 @@ These are all minor breaking changes resulting from enhancements and are not exp
 
 * Remove dplyr verbs superseded in dplyr 1.0.0 (#547, @olivroy)
 
-* Restyle the package and vignettes according to the [tidyverse style guide](https://style.tidyverse.org) (#548, olivroy)
+* Restyle the package and vignettes according to the [tidyverse style guide](https://style.tidyverse.org) (#548, @olivroy)
+
+* `sas_numeric_to_date()` now warns for timezones other than "UTC" due to potential misinterpretation (#583, @billdenney)
 
 # janitor 2.2.0 (2023-02-02)
 

diff --git a/R/sas_dates.R b/R/sas_dates.R
@@ -16,11 +16,16 @@
 #' sas_numeric_to_date(time_num = 3600) # 01:00:00
 #' @family date-time cleaning
 #' @export
-sas_numeric_to_date <- function(date_num, datetime_num, time_num, tz = "") {
+sas_numeric_to_date <- function(date_num, datetime_num, time_num, tz = "UTC") {
   # Confirm that a usable set of input arguments is given
   has_date <- !missing(date_num)
   has_datetime <- !missing(datetime_num)
   has_time <- !missing(time_num)
+  stopifnot(is.character(tz))
+  stopifnot(length(tz) == 1)
+  if (tz != "UTC") {
+    warning("`tz` in SAS does not appear to be stored with the source data; please verify timezone conversion is correct")
+  }
   if (has_date & has_datetime) {
     stop("Must not give both `date_num` and `datetime_num`")
   } else if (has_time & has_datetime) {

diff --git a/man/sas_numeric_to_date.Rd b/man/sas_numeric_to_date.Rd
diff --git a/tests/testthat/test-sas_dates.R b/tests/testthat/test-sas_dates.R
@@ -17,12 +17,18 @@ test_that("sas_numeric_to_date", {
   )
   # NA management
   expect_equal(
-    sas_numeric_to_date(date_num = c(NA, 1), time_num = c(NA, 1), tz = "Etc/GMT-5"),
-    as.POSIXct(c(NA, "1960-01-01 19:00:01"), tz = "Etc/GMT-5")
+    sas_numeric_to_date(date_num = c(NA, 1), time_num = c(NA, 1), tz = "UTC"),
+    as.POSIXct(c(NA, "1960-01-02 00:00:01"), tz = "UTC")
   )
   expect_equal(
-    sas_numeric_to_date(date_num = NA, time_num = NA, tz = "Etc/GMT-5"),
-    as.POSIXct(NA, tz = "Etc/GMT-5")
+    sas_numeric_to_date(date_num = NA, time_num = NA, tz = "UTC"),
+    as.POSIXct(NA, tz = "UTC")
+  )
+  # Timezone warning (#583)
+  expect_warning(
+    sas_numeric_to_date(date_num = 1, time_num = 1, tz = "America/New_York"),
+    regexp = "`tz` in SAS does not appear to be stored with the source data; please verify timezone conversion is correct",
+    fixed = TRUE
   )
 })