tests: test split's new --filter=CMD option

* tests/Makefile.am (TESTS): Add split/filter.
* tests/split/filter: New file.

tests/Makefile.am

@@ -247,6 +247,7 @@ TESTS =						\
   misc/sort-unique				\
   misc/sort-unique-segv				\
   misc/sort-version				\
+  split/filter					\
   misc/split-a					\
   misc/split-bchunk				\
   misc/split-fail				\

tests/split/filter

@@ -0,0 +1,45 @@
+#!/bin/sh
+# Exercise split's new --filter option.
+
+# Copyright (C) 2011 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/init.sh"; path_prepend_ ../src
+print_ver_ split
+
+for total_n_lines in 5 3000 20000; do
+  seq $total_n_lines > in || framework_failure_
+  for i in 2 51 598; do
+
+    # Don't create too many files/processes.
+    # Starting 10k (or even "only" 1500) processes would take a long time,
+    # and would provide little added benefit.
+    case $i:$total_n_lines in 2:5);; *) continue;; esac
+
+    split -l$i --filter='xz > $FILE.xz' in out- || fail=1
+    xz -dc out-* > out || fail=1
+    compare in out || fail=1
+    rm -f out*
+  done
+  rm -f in
+done
+
+# Show how --elide-empty-files works with --filter:
+# split does not run the command (and effectively elides the file)
+# only when the output to that command would have been empty.
+split -e -n 10 --filter='xz > $FILE.xz' /dev/null || fail=1
+stat x?? 2>/dev/null && fail=1
+
+Exit $fail