tests: add a test for cksum

* tests/misc/cksum.sh: Test basic operation.
* tests/local.mk: Reference the new test.

tests/local.mk

@@ -287,6 +287,7 @@ all_tests =					\
   tests/misc/basenc.pl				\
   tests/misc/close-stdout.sh			\
   tests/misc/chroot-fail.sh			\
+  tests/misc/cksum.sh				\
   tests/misc/comm.pl				\
   tests/misc/csplit.sh				\
   tests/misc/csplit-1000.sh			\

tests/misc/cksum.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+# Validate cksum operation
+
+# Copyright (C) 2020 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_ cksum printf
+
+returns_ 1 cksum missing || fail=1
+
+{
+  for offset in $(seq -1 6); do
+    env printf $(env printf '\\%03o' $(seq 0 $offset));
+    env printf $(env printf '\\%03o' $(seq 0 255));
+  done
+} > in || framework_failure_
+
+cksum in > out || fail=1
+printf '%s\n' '4097727897 2077 in' > exp || framework_failure_
+compare exp out || fail=1
+
+Exit $fail