Fix timezone tests

Author: krlmlr

R/Result.R

@@ -119,5 +119,6 @@ tz_force_one <- function(x, timezone) {
   # convert to character in ISO format, stripping the timezone
   ct <- format(x, format = "%Y-%m-%d %H:%M:%OS", usetz = FALSE)
   # recreate the POSIXct with specified timezone
+  # this is the slow part, and it remains slow even if the input is a POSIXlt
   as.POSIXct(ct, format = "%Y-%m-%d %H:%M:%OS", tz = timezone)
 }

R/dbConnect__duckdb_driver.R

@@ -34,6 +34,12 @@
 #'
 #' @return `dbConnect()` returns an object of class [duckdb_connection-class].
 #'
+#' @details
+#' The behavior of `with = "force"` at DST transitions depends on how R handles translation from
+#' the underlying time representation to a human-readable format.
+#' If the timestamp is invalid in the target timezone, the resulting value may be `NA`
+#' or an adjusted time.
+#'
 #' @rdname duckdb
 #' @examples
 #' drv <- duckdb()

man/duckdb.Rd

@@ -164,9 +164,9 @@ test_that("tz_out_convert = force handles invalid timestamps during DST transiti
 
   # The first timestamp should remain valid with full time information
   # The second should be NA (not stripped to date only)
-  expected2 <- c(
-    as.POSIXct("2025-03-30 00:59:00", tz = "Europe/London"),
-    as.POSIXct(NA, tz = "Europe/London")
-  )
+  expected2 <- tz_force_one(timezone = "Europe/London", c(
+    as.POSIXct("2025-03-30 00:59:00", format = "%Y-%m-%d %H:%M:%OS", tzone = "UTC"),
+    as.POSIXct("2025-03-30 01:00:00", format = "%Y-%m-%d %H:%M:%OS", tzone = "UTC")
+  ))
   expect_equal(res2[[1]], expected2)
 })