tests: expand, unexpand: add a test for bounded memory operation

* tests/expand/bounded-memory.sh: New file.
* tests/unexpand/bounded-memory.sh: New file.
* tests/local.mk (all_tests): Add the tests.

tests/expand/bounded-memory.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+# Ensure that expand uses bounded memory.
+
+# Copyright (C) 2025 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 <https://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ expand
+
+vm=$(get_min_ulimit_v_ expand /dev/null) ||
+  skip_ 'failed to determine memory limit'
+
+timeout 0.5 $SHELL -c \
+  "(ulimit -v $(($vm+6000)) \
+    && expand </dev/zero >/dev/null 2>err)"
+ret=$?
+test -f err || skip_ 'shell ulimit failure'
+test $ret = 124 || {
+  fail=1
+  cat err
+  echo "expand used too much memory" >&2
+}
+
+Exit $fail

tests/local.mk

@@ -331,6 +331,7 @@ all_tests =					\
   tests/env/env-S.pl				\
   tests/env/env-S-script.sh			\
   tests/misc/expand.pl				\
+  tests/expand/bounded-memory.sh		\
   tests/expr/expr.pl				\
   tests/expr/expr-multibyte.pl			\
   tests/factor/factor.pl			\
@@ -487,6 +488,7 @@ all_tests =					\
   tests/misc/usage_vs_getopt.sh			\
   tests/misc/getopt_vs_usage.sh			\
   tests/misc/unexpand.pl			\
+  tests/unexpand/bounded-memory.sh		\
   tests/uniq/uniq.pl				\
   tests/uniq/uniq-perf.sh			\
   tests/uniq/uniq-collate.sh			\

tests/unexpand/bounded-memory.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+# Ensure that unexpand uses bounded memory.
+
+# Copyright (C) 2025 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 <https://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ unexpand
+
+vm=$(get_min_ulimit_v_ unexpand /dev/null) ||
+  skip_ 'failed to determine memory limit'
+
+timeout 0.5 $SHELL -c \
+  "(ulimit -v $(($vm+6000)) \
+    && unexpand </dev/zero >/dev/null 2>err)"
+ret=$?
+test -f err || skip_ 'shell ulimit failure'
+test $ret = 124 || {
+  fail=1
+  cat err
+  echo "unexpand used too much memory" >&2
+}
+
+Exit $fail