put base_batchmark unit test in group "basenocran" so it does not run on winbuilder (#2210)

Author: berndbischl

tests/run-base.R

@@ -1,2 +1,2 @@
 library(testthat)
-test_check("mlr", filter = "base")
+test_check("mlr", filter = "base_")

tests/run-basenocran.R

@@ -0,0 +1,4 @@
+library(testthat)
+if (identical(Sys.getenv("TRAVIS"), "true") || identical(Sys.getenv("R_EXPENSIVE_TEST_OK"), "true")) {
+  test_check("mlr", filter = "basenocran_")
+}

tests/testthat/test_base_batchmark.R tests/testthat/test_basenocran_batchmark.R

@@ -1,3 +1,7 @@
+# the whole unit tests currently breaks on CRAN due to a problem with datatable on WB / rdevel
+# see PR here:
+# https://github.com/mlr-org/mlr/pull/2210
+
 context("batchmark")
 
 prev = getOption("batchtools.verbose")