message: Tickle AbslUnparseFlag() to get diff-tool coverage to 100%
diff: @@ -45,4 +45,12 @@ EOF
  "${difftool}" --mode=format "${MY_INPUT_FILE2}" "${MY_INPUT_FILE1}"
  [[ $? -eq 0 ]] || exit 2
  +# Verify that passing a wrong mode will complain
  +"${difftool}" --mode=invalid_mode "${MY_INPUT_FILE2}" "${MY_INPUT_FILE1}"
  +[[ $? -eq 1 ]] || exit 3
  +
  +# test default --mode
  +grep "default:.*format" <("${difftool}" --helpfull) > /dev/null
  +[[ $? -eq 0 ]] || exit 4
  +
  echo "PASS"
  