Allow to parse dates from long numbers

With as.character(), long numbers with many zeros at the end get
converted to scientific notation which the parse of course fails to
recognise. Using format(..., scientific = FALSE) prevents that.

trim = TRUE is necessary for variable length input.

Add tests for these problematic numbers. Tests also check wether
the behaviour of as.character() changes but format()
outperforms as.character() and may be preferred anyway.

NEWS

@@ -1,3 +1,8 @@
+
+BUG FIXES
+
+* allow to parse long numbers such as 20140911000000 as date+time (@jiho, #302)
+
 Version 1.3.3
 -------------------------------------------------------------------------
 

R/parse.r

@@ -695,7 +695,7 @@ fast_strptime <- function(x, format, tz = "UTC"){
   if (is.numeric(x)) {
     out <- rep.int(as.character(NA), length(x))
     nnas <- !is.na(x)
-    x <- as.character(x[nnas])
+    x <- format(x[nnas], scientific = FALSE, trim = TRUE)
     x <- paste(ifelse(nchar(x) %% 2 == 1, "0", ""), x, sep = "")
     out[nnas] <- x
     out

inst/tests/test-parsers.R

@@ -156,6 +156,20 @@ test_that("ymd functions correctly parse dates with no separators and no quotes"
               equals(as.POSIXct("2010-01-02 23:59:59", tz = "UTC")))
 })
 
+test_that("numbers are correctly converted into character for parsing", {
+  # numbers with 000000 at the end are wrongly converted by as.character
+  # which outputs scientific notation
+  expect_that(ymd_hms(20100102000000),
+              equals(as.POSIXct("2010-01-02 00:00:00", tz = "UTC")))
+  expect_that(.num_to_date(20100102000000),
+              equals("20100102000000"))
+  # check for a fix in as.character
+  # if as.character is fixed, consider using it in .num_to_date
+  expect_that(as.character(20100102000000),
+              equals("2.0100102e+13"))
+  expect_warning(ymd_hms(as.character(20100102000000)))
+})
+
 test_that("ymd functions parse absurd formats as NA's", {
   ## should not through errors, just as as.POSIX and strptime
   pna <- as.POSIXct(as.POSIXlt(NA, tz = "UTC"))