NULL is not considered atomic anymore

DESCRIPTION

@@ -4,7 +4,7 @@ Title: Fast and Versatile Argument Checks
 Description: Tests and assertions to perform frequent argument checks. A
     substantial part of the package was written in C to minimize any worries
     about execution time overhead.
-Version: 2.2.0
+Version: 2.3.0
 Authors@R: c(
     person("Michel", "Lang", NULL, "[email protected]",
       role = c("cre", "aut"), comment = c(ORCID = "0000-0001-9754-0393")),

LICENSE

@@ -1,2 +1,3 @@
 YEAR: 2023
 COPYRIGHT HOLDER: Michel Lang
+ORGANIZATION: copyright holder

NEWS.md

@@ -1,3 +1,10 @@
+# Version 2.3.0
+* `NULL` is not longer considered to be atomic in future versions of R
+  (c.f. <https://stat.ethz.ch/pipermail/r-devel/2023-September/082892.html>).
+  To avoid breaking reverse dependencies, checkmate will stick to the old
+  behavior until further notice.
+* Fixed a warning in `checkAtomic()` (#245).
+
 # Version 2.2.0
 * Fixed C compiler warnings for windows
 * Added `checkPermutation` (#230).

R/checkAtomic.R

@@ -3,6 +3,9 @@
 #' @description
 #' For the definition of \dQuote{atomic}, see \code{\link[base]{is.atomic}}.
 #'
+#' Note that `NULL` is recognized as a valid atomic value, as in R versions up to version 4.3.x.
+#' For details, see \url{https://stat.ethz.ch/pipermail/r-devel/2023-September/082892.html}.
+#'
 #' @templateVar fn Atomic
 #' @template x
 #' @inheritParams checkVector

R/checkPathForOutput.R

@@ -18,7 +18,7 @@
 #'  it is both readable and writable.
 #'  Default is \code{FALSE}.
 #' @param extension [\code{character(1)}]\cr
-#'  Extension of the file, e.g. dQuote{txt} or \dQuote{tar.gz}.
+#'  Extension of the file, e.g. \dQuote{txt} or \dQuote{tar.gz}.
 #' @template checker
 #' @family filesystem
 #' @export
@@ -47,7 +47,7 @@ checkPathForOutput = function(x, overwrite = FALSE, extension = NULL) {
   if (!is.null(extension)) {
     qassert(extension, "S1")
     if (!endsWith(x, paste0(".", extension)))
-    return(sprintf("File must have extension '.%s'", extension))
+      return(sprintf("File must have extension '.%s'", extension))
   }
   return(checkAccess(dn, "w"))
 }

R/checkScalarNA.R

@@ -17,7 +17,7 @@ checkScalarNA = function(x, null.ok = FALSE) {
       return(TRUE)
     return("Must be a scalar missing value, not 'NULL'")
   }
-  if (length(x) != 1L || !is.na(x))
+  if (!is.atomic(x) || length(x) != 1L || !is.na(x))
     return(paste0("Must be a scalar missing value", if (null.ok) " (or 'NULL')" else ""))
   return(TRUE)
 }

tests/testthat/test_checkAtomic.R

@@ -47,5 +47,7 @@ test_that("checkAtomic", {
 
   expect_error(assertAtomic(iris), "atomic")
 
-  expect_equal(vlapply(li, is.atomic), vlapply(li, testAtomic))
+  # handling of is.null for future versions of R, see
+  # https://stat.ethz.ch/pipermail/r-devel/2023-September/082892.html
+  expect_equal(vlapply(li, function(x) is.atomic(x) || is.null(x)), vlapply(li, testAtomic))
 })

tests/testthat/test_checkScalarNA.R

@@ -10,3 +10,8 @@ test_that("checkScalarNA", {
 
   expect_error(assertScalarNA(integer(0)), "missing value")
 })
+
+test_that("checkScalarNA on data.frame/data.table (#245)", {
+  df = data.frame(x = 1:2)
+  expect_false(testScalarNA(df))
+})