tests: cksum: ensure --check diagnoses read errors

* tests/misc/read-errors.sh: Add a test case.
Discussed in https://github.com/coreutils/coreutils/pull/167

diff --git a/tests/misc/read-errors.sh b/tests/misc/read-errors.sh
index a9a03d2ebe2b537ed5ad6bbc19fa0aa6ac80cb3b..86bfe0e6fb8cc2790306987bf10685fb49eb0e73 100755 (executable)
--- a/tests/misc/read-errors.sh
+++ b/tests/misc/read-errors.sh
@@ -40,6 +40,7 @@ cksum -a sha3 -l 384 .
 cksum -a sha3 -l 512 .
 cksum -a sm3 .
 cksum -a sysv .
+cksum -a md5 /dev/null | sed 's|/dev/null|.|' | cksum --check
 comm . .
 csplit . 1
 cut -c1 .