tests: rm: add test for today's change in behavior

* tests/Makefile.am (root_tests): Add rm/read-only to the list.
* tests/rm/read-only: New file.

tests/Makefile.am

@@ -37,6 +37,7 @@ root_tests =					\
   rm/fail-2eperm				\
   rm/no-give-up					\
   rm/one-file-system				\
+  rm/read-only					\
   tail-2/append-only				\
   touch/now-owned-by-other
 

tests/rm/read-only

@@ -0,0 +1,56 @@
+#!/bin/sh
+# Ensure that rm -f nonexistent-file-on-read-only-fs succeeds.
+
+# Copyright (C) 2009 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/>.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  rm --version
+fi
+
+. $srcdir/test-lib.sh
+require_root_
+
+cwd=`pwd`
+cleanup_() { cd /; umount "$cwd/mnt"; }
+
+skip=0
+# Create a file system, then mount it.
+dd if=/dev/zero of=blob bs=8192 count=200 > /dev/null 2>&1 \
+                                             || skip=1
+mkdir mnt                                    || skip=1
+mkfs -t ext2 -F blob \
+  || skip_test_ "failed to create ext2 file system"
+
+mount -oloop blob mnt                        || skip=1
+echo test > mnt/f                            || skip=1
+test -s mnt/f                                || skip=1
+mount -o remount,loop,ro mnt                 || skip=1
+
+test $skip = 1 \
+  && skip_test_ "insufficient mount/ext2 support"
+
+# Applying rm -f to a nonexistent file on a read-only file system must succeed.
+rm -f mnt/no-such > out 2>&1 || fail=1
+# It must produce no diagnostic.
+test -s out && fail=1
+
+# However, trying to remove an existing file must fail.
+rm -f mnt/f > out 2>&1 && fail=1
+# with a diagnostic.
+test -s out || fail=1
+
+Exit $fail