small addition to help page for Europe/London issue #84

as well as at least three other (referenced) issues

R/anytime.R

@@ -1,7 +1,7 @@
 
 ## anytime: Use Boost Date_Time to convert date(time) data to POSIXt
 ##
-## Copyright (C) 2015 - 2017  Dirk Eddelbuettel
+## Copyright (C) 2015 - 2018  Dirk Eddelbuettel
 ##
 ## This file is part of anytime.
 ##
@@ -71,7 +71,17 @@
 ##' other hand, \code{c(Sys.Date(), NA)} works as expected parsing as
 ##' type Date with one missing value. See
 ##' \href{https://github.com/eddelbuettel/anytime/issues/11}{issue
-##' ticket 11}) for more.
+##' ticket 11} for more.
+##'
+##' Another known issue concerns conversion when the timezone is set
+##' to \sQuote{Europe/London}, see GitHub issue tickets
+##' \href{https://github.com/eddelbuettel/anytime/issues/36}{36}.
+##' \href{https://github.com/eddelbuettel/anytime/issues/51}{51}.
+##' \href{https://github.com/eddelbuettel/anytime/issues/59}{59}. and
+##' \href{https://github.com/eddelbuettel/anytime/issues/86}{86}. As
+##' pointed out in the comment in that last one, the \code{\link{Sys.time}}
+##' manual page suggests several alternatives to using \sQuote{Europe/London}
+##' such as \sQuote{GB}.
 ##'
 ##' @section Operating System Impact:
 ##' On Windows systems, accessing the \code{isdst} flag on dates or times

tests/gh_issue_84.R

@@ -1,9 +1,30 @@
-si <- sessionInfo()
-if (!grepl("Fedora", si$running, ignore.case=TRUE)) {
-    expected <- "2018-10-01"
-    stopifnot(expected == format(anytime::utctime("2018-10", tz = "UTC")))
-    stopifnot(expected == format(anytime::utctime("2018-10-01", tz = "UTC")))
-    stopifnot(expected == format(anytime::utctime("2018-10-01 00", tz = "UTC")))
-    stopifnot(expected == format(anytime::utctime("2018-10-01 00:00", tz = "UTC")))
-    stopifnot(expected == format(anytime::utctime("2018-10-01 00:00:00", tz = "UTC")))
-}
+## See discussion in #84 -- this is more likely an issue with Europe/London
+##
+## si <- sessionInfo()
+## if (!grepl("Fedora", si$running, ignore.case=TRUE)) {
+##     expected <- "2018-10-01"
+##     stopifnot(expected == format(anytime::utctime("2018-10", tz = "UTC")))
+##     stopifnot(expected == format(anytime::utctime("2018-10-01", tz = "UTC")))
+##     stopifnot(expected == format(anytime::utctime("2018-10-01 00", tz = "UTC")))
+##     stopifnot(expected == format(anytime::utctime("2018-10-01 00:00", tz = "UTC")))
+##     stopifnot(expected == format(anytime::utctime("2018-10-01 00:00:00", tz = "UTC")))
+## }
+
+
+Sys.setenv(TZ = "Europe/London")
+x <- c("2016-01-01 00:00", "2016-10-01 00:00",
+       "2016-12-09 00:00", "2016-12-09 10:00")
+anytime::utctime(x, tz = "UTC")
+anytime::utctime(x, tz = "UTC", useR=TRUE)
+
+Sys.setenv(TZ = "UTC")
+x <- c("2016-07-01 00:00", "2016-07-01 00:00",
+       "2016-12-09 00:00", "2016-12-09 10:00")
+anytime::utctime(x, tz = "UTC")
+anytime::utctime(x, tz = "UTC", useR=TRUE)
+
+Sys.setenv(TZ = "Australia/Melbourne")
+x <- c("2016-01-01 00:00", "2016-10-01 00:00",
+       "2016-12-09 00:00", "2016-12-09 10:00")
+anytime::utctime(x, tz = "UTC")
+anytime::utctime(x, tz = "UTC", useR=TRUE)