tests: ptx: ensure bad unicode is supported

* tests/ptx/ptx-overrun.sh: Ensure bad_unicode() is processed.

Author: oech3

tests/ptx/ptx-overrun.sh

@@ -18,8 +18,9 @@
 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
 print_ver_ ptx
 
-# Ensure this input is processed
+# Ensure these inputs are processed
 printf '%s' '012345678901234567890123456789🛠' | ptx || fail=1
+bad_unicode | ptx || fail=1
 
 # Trigger a heap-clobbering bug in ptx from coreutils-6.10 and earlier.
 # Using a long file name makes an abort more likely.